KENDRIYA VIDYALAYA SANGATHAN
SILCHAR REGION
STUDY MATERIAL
CLASS X
SCIENCE
2014-2015
1
KENDRIYA VIDYALAYA
SANGHATAN
STUDY MATERIAL
OF
CLASS – X
2014 – 2015
2
INDEX
PART OF THE STUDY MATERIAL :A)
B)
C)
CHEMISTRY
BIOLOGY
PHYSICS
 GIST OF THE LESSON:O KEY CONCEPTS
O IMPORTANT DEFINITIONS
O USEFUL DIAGRAMS
O QUESTIONS
O HOTS
AND
VALUE
QUESTIONS.
O MIND MAPS.
3
BASE
CLASS X - SCIENCE
Chief Patron
Shri. AvinashDikshit
Commissioner
KVS New Delhi
Patron
Shri. SomitShrivastav
Deputy Commissioner
KVS, Silchar Region
Advisor
Shri. R.Senthil Kumar
Assistant Commissioner
KVS, Silchar Region
Subject Contributors
Mr. MANIK SUTRADHAR
PGT(Chem)
K V ONGC SRIKONA
Mrs. JAL SMITH
PGT(Phy)
KV MASIMPUR
4
Syllabus
Unit
No
Name
I
Chemical Reaction and Equation
II
Acids, bases and salts
III
Metals and non-metals
IV
Carbon and its compounds
V
Periodic classification of elements
VI
Life Processes
VII
Contrl& Coordination
VIII
How Do Organisms Reproduce ?
IX
Heredity And Evolution
X
Light : Reflection and Refraction
XI
Human eye and colorful world
XII
Electricity
XIII
Magnetic effect of current
XIV
Sources Of Energy
XV
Our Enviroment
XVI
Management of natural resources
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1. Chemical Reaction and Equation
 Chemical reaction involves a change in the physical, chemical properties composition and physical
state of substance.
 Chemical equation → symbolic representation of reactants and products using their chemical
formula.
 Writing of chemical equation
Two types
1. Word Representation
Example: Magnesium + oxygen → Magnesium Oxide
2. Symbol Representation
Example: Mg +O₂ → MgO
 A Chemical Equation contains
 Reactants →written on left side
 Products → written on right side
 Arrow which separate the both
Mg +O₂ → MgO
↓
↓
Reactants Products
 Symbols for physical state of reactants and products.
 Solid (s)
 Liquid (l)
 Gas (g)
 Aqueous Solution (aq)
 Gas Equation (↑)
 Precipitate formula (↓)
 Direction of reaction (→)
 Chemical Reaction →developed on Law of conservation of Mass → Means mass of
reactantsconsumed equal to the mass of the products formed
 Balanced chemical equation
Number of atom of Reactants = Number of atom of products
 Unbalanced chemical equation
Number of atom of reactant ≠ Number of atom of products
 The following steps are involved the Balancing chemical equation.
1. Determining the reactants and products in a reaction.
2. Counting the number of atoms of each on both sides.
3. Selecting the elements that occur for the least number of the times in the equation.
4. Changing the coefficient of the molecules of reactant or product as required.
Eg: Iron +Steam → Magnetic Oxide of Iron +Hydrogen
1. Fe +H₂O →Fe₃O₄ +H₂
 Element
No. of atoms on L.H.S
No. of atoms on R.H.S
Fe
1
3
H
2
2
O
1
4
Select elements with highest No. of atoms
 Fe +4 H₂O → Fe₃O₄ +H₂
Start balancing with different elements
 3Fe +4 H₂O → Fe₃O₄ +H₂
 3Fe +4 H₂O → Fe₃O₄ +4H₂
6
Balancing equation
 3Fe +4 H₂O → Fe₃O₄ +4H₂
2. KClO₃ → KCl +O₂
2KClO₃ → 2KCl +3O₂
(Unbalanced equation)
(balanced equation)
 Types of Chemical Reaction
1. Combination Reaction: Two or more reactants combine to form a single
product.
Example: C + O₂ → CO₂
CaO + H₂O → Ca(OH) ₂
2. Decomposition reaction: A substance splits into two or more substances it is further three types.
a. Thermal Decomposition: takes place by absorption of heat.
Example: CaCO₃ (s) → CaO (s) +CO₂ (g)
b. Electrolytic Decomposition: Take place when electric current is passedthrough the compound in
molten or aqueous solution.
Example: 2 H₂O → 2H₂ (g) + O₂ (g)
c. Photo decomposition: By absorption of light
Example: 2AgBr → 2Ag+ Br₂
3. Displacement Reaction: the reaction in which one element displaces another element in a
compound.
Example: Mg +CuCl₂→ MgCl₂ +Cu
4. Double Displacement Reaction: Exchange of ions between the reactants.
Example: MgO +CaS →MgS +CaO
5.Precipitation Reaction: Two clear solutions combine to form an insoluble salts.
6. Oxidation and Reduction:
Oxidation: Addition of oxygen or removal of hydrogen.
Reduction: Addition of hydrogen or removal of oxygen.
 Corrosion: Eating up of metals due to attack of atmosphere gases or the surface of metals is called
corrosion.
 Causes damage to car bodies, brides, railing etc.
 Corrosion of iron called rusting
 Protection:
 Oiling and Greasing the metal articles
 Paint
 Galvanization.
 Rancidity: Oxidation of fat and oil.
 Prevention:
 Using Antioxidants.
 Packing food in nitrogen gas.
HOTS
Q.1 What Chemical compounds is used in white wash of walls? What happens when we mix it with water?
What reaction takes place on the walls after thewhite wash?
Ans. Quicklime (CaO), is used for white wash of walls.
CaO + H₂O → Ca(OH) ₂
On wall Ca(OH) ₂ + CO₂ → CaCO₃ +H₂O
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Q.2When Lead Nitrate combines with Potassium Iodide a yellow precipitate forms
a) Name the precipitate
b) Show the Chemical Reaction?
c) Name the type of Reaction?
Ans. a) Lead Iodide.
b) Pb(NO₃)₂ (aq) + KI(aq) →
PbI₂ (s) + KNO₃ (s)
Lead Nitrate Potassium Iodide Lead Iodide Potassium Nitrate
Q.3. Why a few drops of sulphuric acid are added into water before electrolysis?
Ans. Pure water is a poor conductor of electricity. A few drops of Sulphuric acid are added to make it a
good conductor of electricity.
Q.4 When Carbon dioxide is passed through lime water, first it turns milky and on further passing the gas
milkiness disappear explain why?
Ans.If excess of CO₂ gas is passed through lime water, the milikiness disappears andthe solution again
becomes clear this is due to the change of insoluble CaCO₃ in to soluble calcium hydrogen carbonate as
follows.
CaCO₃ +CO₂ + H₂O → Ca(HCO₃)₂
Q.5The gases H₂ and Cl₂ do not react with each other even if kept together for a long time however in the
presence of sunlight, they readily combine. What does actually happen?
Ans. We know that in a chemical reaction energy is needed to break the bonds that in the reacting
molecules so that they may combine to form the products in the present case, sunlight is the source of
energy in the form of photons. Theenergy made available helps in breaking the bonds present in the reactant
molecules and chemical reaction leading to the formation of HCl gas take place.
H₂ (g) + Cl₂ (g) → 2HCl (g)
Q.6Why do potato chips manufacturers fill the packets with nitrogen gas?
Ans.This is done in order to flush out any air or oxygen present in the packet. In their absence chips will not
get rancid.
Q.7 Based on the reaction given below arrange the metals involved in these reactions decreasing order of
reactivity and also write nature of reactions.
a. Zn + CuSO₄ → ZnSO₄ + Cu
b. Cu + 2AgNO₃ → Cu(NO₃)₂ +Ag
c. Zn + FeSO₄ → ZnSO₄ + Fe
d. Fe + CuSO₄ → FeSO₄ + Cu
Ans.a. Since Zn displaces Cu from CuSO₄, it is more reactive than Cu
b. Cu displaces Ag from Ag from AgNo₃, it is more reactive than Ag
c. Zn displaces Fe from FeSO₄, it is more reactive than Fe.
d. Fe displaces Fe from CuSO₄, it is more reactive than Cu
Decreasing order of Reactions Zn> Fe> Cu > Ag
All are Displacement Reactions.
Q.8 Solid calcium Oxide was taken in a container and water was added slowly to it
i. State two observation made in the experiment.
ii. Write the name of the chemical formula of the product.
Ansi.Water start boiling and hissing noise will be produced
ii. Calcium Hydroxide will be formed
CaO (s) + H₂O (aq) → Ca (OH)₂ (s) + Heat
Q.9 Name the substance Oxidized and Reduced in the Chemical Reaction
MnO₂ + 4HCl → MnCl₂ +Cl₂ +2H₂O
8
Ans. HCl → Oxidised
MnO₂ → Reduced
Q.10 On what basic Reaction is black and white photography based?
Ans. Black and white photography is based on the decomposition of AgBr in the presence of sunlight to
produce Silver.
2AgBr (s) → 2Ag + Br₂
Long Answer Questions.
Q.1 How can a balanced equation be made more informative? Explain with example?
Ans. (i) Physical states of the substance can be indicated by using the symbol (s) form solid, (l) for liquid,
(g) for gas and (aq) for aqueous solution.
(ii) Gaseous product may be represented by an arrow upward (↑) and a Precipitate formed by an arrow
downward (↓).
(iii) Concentrations of the solutions can be indicated by writing the symbol ‘dil’ for dilute and ‘conc’
for concentrated solution.
(iv) Heat changes by indicating by writing ‘+Heat’ with the products for exothermic reaction and ‘+Heat
with the reactants for endothermic reactions.
(v) Conditions of temperature and pressure and the presence of catalyst can be Indicated on the arrow.
Eg: Zn (s) + dil. H₂SO₄(aq) → ZnSO₄ (aq) + H₂(g) ↑
Q.2 Explain the following with suitable example?
a. Exothermic Reaction b. Endothermic Reaction
Ans. a. Exothermic Reaction: Those reactions in which heat is evolved during the reaction are called
exothermic reaction.
Eg: C (s) + O₂ (g) → CO₂ (g) + Heat
b. Endothermic Reaction: Those reactions in which heat is absorbed during the reaction are called
endothermic reaction.
Eg: C (s) + H₂O (g) + Heat → CO (g) +H₂ (g)
Q.3 (a) Why is combustion reaction an oxidation reaction?
(b) How will you test whether the evolved in a reaction is hydrogen?
(c) Why does silver not evolve hydrogen gas on reacting with dilute sulphuricacid
Ans. (a) Combustion reaction is an oxidation reaction because it is always carried in the presence of air or
oxygen for example
CH₄ (g) +2O₂ (g) → CO₂ (g) +2H₂O (l)
(b) Bring a burning match stick close to the mouth of the tube from which hydrogen gas escapes. The
gas will immediately catch fire and this will be accompanied by pop sound.
(c) Silver is less reactive metal in the sense that it occupies a place below hydrogen in the reactivity series.
Therefore it does not evolve hydrogen gas on reacting with either dilute
sulphuric acid or dilute hydrochloric acid.
Q.4 Identify the type of reaction in the following?
(a) ZnCO₃ (s) + 2HCl (aq) → ZnCl₂(aq) +H₂CO₃ (aq)
(b) 2NaBr (aq) + Cl₂ (g) → 2NaCl (aq) + Br₂ (aq)
(c) 2CuO (s) → 2Cu (s) +O₂ (g)
(d) 2Na (s) + Cl₂ (g) → 2NaCl (s)
Ans. (a) Double Displacement Reaction
(b) Displacement Reaction
(c) Decomposition Reaction
(d) Combination Reaction
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Q.5 (a) Why can not a Chemical change be normally reserved?
(b) Why it is always essential to balance a chemical equation?
(c) Can rusting of iron take place in distilled water?
(d) How will you know whether a sample of cheese has become rancid or not?
Ans (a) In a chemical change the products are quite different from the reactants. Therefore, it cannot be
normally reversed.
(b) A chemical equation has to be balanced to meet the requirement of the law of conservation of
mass. According to the law, the total mass of reacting species taking part in the reaction is the same as that
of the products formed since there is a direct relationship between the mass of the different Species and
their number, it is always essential to balance a chemical equation.
(c) No, rusting of iron cannot take place in distilled water because it neither contains dissolved oxygen
nor carbon dioxide. Both are essential for the rusting of iron
(d) It gives bad smell and it taste also changes.
SHORT ANSWER QUESTIONS
Q.1 In the following reaction:
MnO2 + 4HCl→ MnCl2 +2H2O+Cl2
a) Name the substance oxidized.
b) Name the substance reduced.
Ans .a) HCl
b) MnO2
Q.2 Suggest two methods to prevent rancidity?
Ans. a) By adding antioxidant.
b) By flushing the food articles.
Q.3 Can we place silver nitrates solution in an iron vessel? Why or Why not?
Ans. No, we cannot .Because iron is more reactive than silver .The following displacement reaction takes
place:
Fe +2AgNO 3 → Fe(NO 3)2+2Ag
Q.4What is an oxidizing agent?
Ans .An oxidizing agent is a substance which gives oxygen or gains hydrogen, that is oxidises other and
itself reduced.
Q.5 Why Hydrogen Peroxide kept in colored bottles?
Ans. This is done to cut off light because it decomposes into water and oxygen in the presence of light.
Q.6 The substance oxidized in a redox reaction is called……………………… agent.
Ans. Reducing agent
Q.7 What do you mean by Rancidity?
Ans. The oxidation of oil and fats due to aerated oxygen is called rancidity.
Q.8 What “aq” stands for?
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0
Ans.Itsstand for aqueous solution.
Q.9 Name one metal which does not corroded?
Ans. Gold
Q.`10 Does hydrogen gas support combustion?
Ans .No, it does not support combustion .Because it is highly combustible in nature.
1
1
2. Acids, bases and salts
 Acids are the substances which are sour in taste.
OR
The substance which release Hydrogen ions when dissolve in water. Example: HCl,H2SO4
 Bases are bitter in taste.
OR
Substance which gives hydroxide ionswhen dissolved in water. Example:NaOH, KOH.
 Acid-Base Indicators
These are of two types:
 Show change in color .Example: Litmus solution, methyl orange.
 Show change in odor. Example:Onion,vanilla essence.
Indicator
Litmus
Methyl orange
Phenolphthalein
Color in neutral solution
Purple
Orange
Colorless
Color in acidicsolution
red
red
colorless
Color in basic solution
blue
Yellow
Yellow
 Chemical properties of Acids: Action with metals
Metal +acid → Metal salt +hydrogen gas
Example: Zn +H2SO4→ZnSO4+H2
 Action with metal oxides
Metal oxides+ Acid→ Salt+ water
Example: CaO + 2HCl →CaCl2+H2O
 Action with metal carbonates and hydrogen carbonates
Example: CaCO3+2HCl→CaCl2+H2O+CO2
2NaHCO3+ H2SO4→Na2SO4+H2O+CO2
 Chemical properties of bases
 Action with metals
Metal+ Bases→ Salts+ Hydrogen gas
Example: 2NaOH+Zn→Na2ZnO2+H2
 Action with Non-metal oxides
Bases+ Non-metal oxides →Salts + water
Example: NaOH+CO2→ Na2CO3+H 2O
 Neutralization Reaction
Acid+ base →Salt +water
 Acid and base give ions (H+ by Acid) and (OH_ by Base) in their aqueous solution. Hence they have
tendency to conduct electric current.
 pH scale:- used to check acidity and basicity.
It ranges from 1 to 14.
 For Neutral Solution pH=7
Acidic Solution pH<7
 Basic Solutions pH>7
 SALTS:- Combination of positive and negative charge .Example: NaCl,KNO3
 Common salts-NaCl
 Bleaching powder (calcium oxychloride)
CaOCl2+Cl2→CaOCl2+H2O
USES:
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2
In textile industry, laundry, paper industry.
 Baking soda (sodium hydrogen carbonate) (NaHCO3)
NaCl+H2O+ NH3 + CO2→NH4Cl + NaHCO3
USES:
As antacid, as fire extinguisher,additives in food and drinks
 Washing Soda(sodium carbonatedecahydrate) (Na2CO3.10H2O)
USES:
In laundry, removing hardness, manufacture of soap, paper etc.
 PLASTER OF PARIS (CaSO4.1/2H2O)
Chemical Name: Calcium Sulphate Hemihydrates
Preparation- CaSO4.2H2O --heat→CaSO4.1/2H2O+ 3/2 H2O
USES:
Setting fractured bones, in making toys, in making surface smooth.
HOTS
Q.1 Why we should not keep curd in cooper or brass vessel .What treatment should be given to these
vessels before use.
Ans .Curd is acidic in nature .it reacts with Cu & brass to form toxic compound and make food toxic for
consumption .so for protection these vessels have to be coated with a thin layer.
Q.2 Glucose, alcohol contains hydrogen yet their solutions do not turn blue litmus red. Why.
Ans. They do not produce H+ ion in solution.
Q.3 Name two metals which react with sodium hydroxide solution to produce hydrogen gas .give the
reaction.
Ans .Zinc and Aluminum
2NaOH+2Al→2NaAlO2+3H2
2NaOH+Zn→Na2ZnO2+H2
Q.4 Rain water and tap water conduct electricity but distilled water does not .Explain why.
Ans. Distilled water does not contain any acid, base or salt. Whereas tap or rain contain gases of air like
CO2,SO2,and NO2etc. When dissolve in water form acid .ex.CO2+H20→H2CO3
Q.5. Which is more acidic &why.
a)A solution with pH value of 6.0.
b) A solution with pH 5.0
Ans.[ H+] in solution with pH= 5.0 is 10-5M.
[H+] in solution with pH = 6.0 is 10-6M.
As 10-5>10-6, hence solution with pH = 5 is more acidic than the solution with pH = 6.0.
Q.6 How is Plaster of Paris is prepared .What reaction take place when it sets to hard.
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3
Ans .Plaster of Paris is prepared by heating Gypsum to a temperature of 1000C.
CaSO4.2H2O --heat→CaSO4.1/2H2O + 3/2H2O
On mixing with water, it reactsand become a hard mass due to formation of Gypsum again .the reverse
reaction take place.
Q.7What is difference between a base and a alkali .explain with suitable example.
Ans. Base is the substance which reacts with acid to form salt and water. These are metallic oxide or
hydroxide including NH4OH. Example: CaO, MgO, and NaOH etc.
The bases which is soluble in water and give OH- ions, called alkali .Thus CuO is a base but not an alkali.
Q.8 What is Acid rain? What is its pH? How does it affect the aquatic life?
Ans. When it rains, gases like CO2,SO2,etc. of the atmosphere dissolve into it &hence its pH<7 .When pH
of rain below 5.6 ,it is called acid rain .When this acid rain flow into the river,the pH of river water falls
and the survival of aquatic life become difficult.
LONG ANSWER QUESTION
Q.1 Explain the importance of pH in daily life.
Ans. a) In humans and plants.-In human body the reaction occur at pH ranges from 7.0 to 7.8 .if it falls then
survival is difficult.
Plants have a healthy growth only when the soil has a specific pH range which should be neither
alkaline nor highly acidic.
b)In digestive system – HCl in stomach help in digestion of food. It help to kills the bacteria that may enter
into the stomach along with the food.
c)Tooth Decay caused by acids – Acid is produced in the mouth by degradation of sugar .saliva produced in
the mouth is alkaline help to neutralize the acids.
d) Self defense of animals and plants through chemical welfare.
Q.2Solutions A, B, C,D have pH values 3,4,5,6 respectively. Arrange them in increasing order of acidic
characteristic .giving reason.
Ans. D<C<B<A
Increasing order
H+ ion conc. of A, B,C,D are 10-3,10-4,10-5,10-6 respectively. As higher the [H+] more acidic is the
solution.
Q.3Why tartaric acid added into baking soda to get baking powder.
Ans. Tartaric acid is added to neutralize the sodium carbonate formed on heating if it is not added; the cake
would taste bitter due to presence of sodium Carbonate.
Q.4. (a) How is bleaching powder prepared. (b) What happens if bleaching powder is exposed to air for a
long time. (c) Giveitsuses.
Ans. a) Ca (OH)2+Cl2→CaOCl2+H2O
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b) CaOCl2+CO2→CaCO3+Cl2
c) USES
In paper industry, textile industry, laundry.
Q.5. what is the difference between:
a) Strong acid and weak acid.
b) Strong base and weak base
Ans .Acids like HCl,H2SO4 which dissociate completely in the aqueous solution to produce H+ ions called
strong acids .Acids like CH3COOH,H2CO3 which dissociate only partially in the aqueous solution to
produce a small amount of H+ ion, called weak acid.
Bases like NaOH, KOH etc. which dissociate completely in the aqueous solution to produce a large amount
of OH- ions, called strong base .While NH4OH,Ca(OH)2 etc. which dissociate only partially in the aqueous
solution called weak base.
SHORT ANSWERS QUESTION
Q.1 Classify the following as strong and weak acids.
a) HCl
b) H2SO4
c) H3PO4
d) HNO3
e) CH3COOH
Ans. Strong acid: - HCl, H2SO4, HNO3
Weak acid: H3PO4, CH3COOH
Q.2Aceic acid is highly soluble in water but is still a weak acid .Why.
Ans. The strength of an acid is not related to its solubility in water .but depend on extent of dissociation
.Itdissociates less so weak acid.
Q.3Where is Hydrogen used as fuel.
Ans.As a Rocket Fuel.
Q.4 Define pH.
Ans. It is the magnitude of the negative power to which 10 must be raised to express the Hydrogen ion
conc. of the solution in moles per liter.
Q.5A doctor applied surgical bandage in the fractured bones of a patient after making them wet. What
changes are likely to occur?
Ans. Surgical bandage is made up of plaster of Paris .When applied on the fractured bones after making
them wet, it changes into hard mass called Gypsum.
CaSO4.1/2H2O+3/2H2O→ CaSO4.2H2O.The hard mass keeps the bone in the proper position.
1
5
3. Metals and non-metals
 Elements are classified broadly into two categories on the basis of properties:
 Metals: Iron, Zinc, Copper, Aluminium etc.
 Non- metals: Chlorine, Nitrogen, Hydrogen, Oxygen, Sulphur etc.
 Apart from metals and non-metals some elements show properties of both metals and non-metals,
Example: Silicon, Arsenic, Germanium.They are called metalloids.
Comparison of physical and chemical properties of metals and non – metals:Sl.
Property
Metals
Non-Metals
No.
1
Physical State
Metals are solid at room
Non-metals generally exist as
temperature. Except mercury solids and gases, except Bromine.
and gallium.
2
Melting and boiling Metals generally have high
Non-metals have low m.pt and b.pt
points
m.pt and b.pt except gallium except diamond and graphite.
and caesium.
3
Density
Generally high.
Generally low.
4
Malleability and
Malleable and ductile.
Neither malleable nor ductile.
Ductility
5
Electrical and
Good conductors of heat and Generally poor conductors of heat
thermal conductivity electricity.
and electricity except graphite.
6
Luster
Poses shining lustre.
Do not have lustre except iodine.
7
Sonorous sound
Give sonorous sound when
Does not give sonorous sound.
struck.
8
Hardness
Generally hard except Na, K Solid non-metals are generally soft
except diamond.
Comparison of Chemical Properties of Metals and Non-metals:1
Reaction with
Metal + Oxygen Metal oxide
Non-metal + Oxygen  Non-metal
Oxygen
oxide
C+
4Na(s) + O2(g)  2Na2O(s)
O

CO
4Al(s) + 3O2(g)  2Al2O3
2
2
Metals form basic oxides.
Zn
S + O2 SO2
and Al form amphoteric oxides (they Non-metals form acidic oxides.
show the properties of both acidic
CO and H2O are neutral oxides(they
and basic oxides)
are neither acidic nor basic in nature).
Most of the metal oxides are
Non-metal oxides are soluble in water
insoluble in water. Some of them
They dissolve in water to form acid.
dissolve to form Alkali
example SO2 +H2O  H2SO3
Na2O(s) + H2O(l)  2NaOH(aq)
2
Reaction with
Metals react with water to form metal Non-metals do not react with water,
water
oxides or metal hydroxide and H2 gas steam to evolve hydrogen gas. Because
is released.
2Na(s) + Non-metals cannot give electrons to
hydrogen in water so that it can be
2H2O(l)  2NaOH +
released as H2 gas.
H2(g) + heat
3
Reaction with
Non-metals do not react with acids to
Metal + Acid  Metal salt +
dilute Acids
release H2 gas
ReasonHydrogen
Non-metals cannot loose electrons and
Mg(s)+2HCl(aq)MgCl2(aq)+H2(g) give it to Hydrogen ions of acids so
that the gas is released.
2Na(s)+H2SO4Na2SO4(aq)
1
6
4
Reaction with
salt solutions
5
Reaction with
Chlorine
6
Reaction with
Hydrogen
+H2(g)Metal+HNO3H2 gas is not
displaced.
Reason- HNO3 is strong oxidizing
agent. It oxidises hydrogen to water.
When metals react with salt solution,
more reactive metal will displace a
less reactive metal from its salt
solution.
CuSO4(aq)+Zn(s)ZnSO4(aq)+Cu(s)
Metal + Chlorine  Metal Chloride
ionic bond is formed. Therefore Ionic
compound is obtained.
2Na + Cl2 2NaCl
Metals react with hydrogen to form
metal hydride.
This reaction takes place only for
most reactive metals.
2Na(s) + H2(g)  2NaH(s)
When non-metals react with salt
solution, more reactive non-metal will
displace a less reactive non-metal from
its salt solution.
2NaBr(aq)+Cl2(g)2NaCl(aq)+Br2(aq)
Non-metal + Chlorine  Non-metal
Chloride.
Covalent bond is formed. Therefore
covalent compound is obtained.
H2(g) + Cl2 2HCl
Non-metals react with hydrogen to
form hydrides
H2(g) + S(l)  H2S(g)
Properties of ionic compounds
1. Physical nature:solid and hard due to strong force of attraction. (generally brittle)
2. Melting point and boiling point:have high M.P and B.P, as large amount of heat energy is required
to break strong ionic attraction.
3. Solubility: soluble in water and insoluble in kerosene and pertrol.
4. Conduction of electricity:ionic compounds in solid state-----does not conduct electricity.
Reason—Ions can not move due to rigid solid structure. Ionic compounds conduct electricity in
molten state.
Reason-- Ions can move freely since the electrostatic forces of attraction between the oppositely
charged ions are overcome due to heat.
Occurrence of metals.
It occurs in Earths crust, sea-water
Minerals
Ores
Elements or compounds, occuring naturally
percentage
Minerals that contain very high
in the earth’s crust
of a perticular metal and these metals can be
extracted economically on a large scale.
e.g Bouxite ore → Aluminium
Haematite → Iron
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7
HOTS
1
8
Q.1 GIVE REASONS:
a) Platinum, gold, and silver are used to make jeweler
b )Sodium ,potassium and lithium are stored under oil.
c) Aluminum is a highly reactive metal; still it is used to make utensils for cooking.
Ans. Platinum, gold, and silver are highly unreactive metals .Therefore; they do not undergo corrosion due
to attack by moisture and atmospheric gases. Further, they are highly malleable and ductile. Because of
these properties, i.e, resistance to corrosion, high malleable and ductile, these are used to make jewelers.
b) Because they are readily attacked by O2 present in air to form their respective oxides .they also react with
moisture present in air producing H2 gas which sometimes catches fire and causes accidents .so to protect
from such accident they are in oil.
c) When exposed to then moist air a layer of Aluminum oxide is formed .now with this formation it
become resistance to corrosion and used to make utensils.
Q.2 What are amphoteric oxides .give examples of two amphoteric oxides.
Ans, Oxides which react with both acids and bases to form salts and water are called amphoteric oxides.
Two examples are:-Zinc Oxide and Aluminum Oxide.
Q.3 Which metals are called strategic metals. Give a few examples of the uses to which they are put.
Ans. Metals like titanium, chromium, zirconium etc. which are used in the country defense are strategic
metals. These metals and their alloys are used in the atomic energy, jet engine and in making high grade
steel.
Q.4 What is Anodizing. For what purpose is it done?
Ans. Anodizing is a process of coating a thick layer of aluminum layer on the surface of aluminum articles
.It protect the the aluminum from corrosion.
Q.5 ‘E’ is an element which is one amongst Copper, Zinc,and Aluminum and Iron,it show following
properties:
a) One of its ore is rich in E2O3
b) E2O3is not attacked by water.
c) It forms two chlorides ECl2 and ECl3. Name the element and justify your answer.
Ans. As it form two chlorides it mean element has variable valency of 2 &3 .Out of the element listed iron
exists in divalent and trivalent forms.
a) The ore rich in Fe2O3is Hematite.
b) Hematite is not attacked by water.
c) The two chlorides are FeCl2 and FeCl3.
Q.6 An element reacts with oxygen to form an oxide which dissolves in dil. Hydrochloric acid. The oxide
formed also turn a solution of red litmus blue. Is the element a metal or non-metal? Explain with the help of
example.
Ans. The oxide of the element is basic as it turns red litmus blue .This means that the element is a metal
(M).Let the metal be sodium (Na).The chemical equation that are involved are:
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9
4Na + O2→ 2Na2O
Na2O +H2O→ 2NaOH
Na 2O+ 2HCl →2NaCl +H 2O
Q.7 Give reason for the following;
a) Zinc can displace copper from copper sulphate solution.
b) Silver articles become black sometime when exposed to air.
c)A metal sulphide is converted to its oxides to extract the metal from sulphide ore.
Ans .a): Zinc is placed above copper in the activity series. It is more reactive than Cu. Therefore; it can
easily displace copper from copper sulphate solution.
Zn +CuSO4 →ZnSO4 +Cu
b)Air contain traces of hydrogen sulphide gas. Sulphide has a tendency to combine with H2S to form silver
sulphide which is black in color .On account of this, silver article become black.
c) Metal sulphide is normally converted into oxide by heating with excess of air .This process is called
roasting. Actually, the oxide of metal which is formed can be easily reduced to the metallic form by
reduction with carbon or some electropositive element.
Q.8 a)Distinguish between roasting and calcinations .
Ans.
CALCINATION
It is carried out in absence of air or oxygen.
Metal carbonate→ Metal Oxide + CO2
ROASTING
It is carried out in presence of excess of air.
Metal Oxide+ Carbon→ Metal + CO2
Q.9 a) Are all pure liquid bad conductor of electricity.
b) Name a liquid which is a good conductor of electricity but does not electrolysis on passing electric
current.
c) If pure water is used, no electrolysis takes place. Why
d)Name one practical application based on the phenomenon of electrolysis.
Ans. a) NO, there is exception also. Mercury in pure state is a good conductor of electricity.
b)Mercury .but does not undergo Electrolysis.
c) Pure water does not dissociate into ions on passing electric current.
d) The process of electroplating on the surface of metals is based on the phenomenon of electrolysis.
Q.10 What is the Activity series of metals.
Ans.The relative electron releasing tendency of some important metals are summed up in the activity series.
Q.11 Define the following.
a) Metal refining
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0
b)Alloy
c) Amalgam
d) Ore
ans. a) Metal Refining:-The conversion of crude metal into pure metal.
b) Alloy: - The homogenous mixture of more than one metal or even metal and non-metal.
c) Amalgam: -It is an alloy in which mercury is one of the components.
LONG ANSWER QUESTION
Q.1Corrosion of metal is not always harmful. Illustrate.
Ans. Corrosion is a very harmful process resulting in slow eating up of a metal. But corrosion of aluminum
is useful .A layer of aluminum oxide formed as a result of chemical reaction gets deposited on the surface
of metal .It forms a protective coating on the surface and prevents the attack of water ,air and acids.
Q.2 Why are positively charged ions called cations while negatively charged called anions.
Ans. When electric current is passed through the molten or aqueous solution of an electrolyte, the positively
charged ions migrate towards the negative electrode or cathode. They are therefore, called cations. The
negatively charged ions migrate towards the positive electrode or anode. They are therefore, called anion.
Q.3 Explain, why solid sodium chloride does not conduct electricity but in the molten state or in the
aqueous solution, it is a good conductor of electricity.
Ans .In solid state the movement of ions is not possible due to strong inter-ionic attraction while in molten
state the ion of sodium chloride are free to move and conduct electricity.
Q.4 Why do atoms combine.
Ans. Atoms combine to form compounds so as to acquire the stable electronic configuration of the nearest
noble gas, for example,the electronic configuration of Na is 2,8,1 and Cl is 2,8,7 .The Na has one electron
more than neon gas configuration and Cl has one electron less than argon gas configuration so in order to
get noble gas configuration Na loses one electron and Cl accept the electron.
Q.5 Why is sodium chloride soluble in water but not in kerosene or oil.
Ans. Water ispolar in nature so NaCl dissociate in their ions and dissolve, while kerosene is a non- polar
solvent so NaCl doesn’t dissociate and dissolve.
Q.6a) Why metals conducts electricity.
b) Name three common compound forms in which metals occur in nature.
ans. a) Because the attraction of the nucleus on the valence electron is minimum. Hence, electron is free to
move.
b) Three common compound forms in which metal occur in nature are:
I.
II.
III.
Oxides e.g., Bauxite (Al 2O 3.2H 2O)
Sulphides e.g., Iron Pyrites (FeS2)
Carbonates e.g., Calamine (ZnCO3)
Q.7 Oxides of the metals which are high in the activity series are not reduced by carbon. How will you
account for it?
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1
Ans .Metals which lie high in the activity series is reactive in nature the oxides of these metals are
extremely stable. Moreover, the metals present in these oxides are very strong reducing agents themselves
.They cannot loseoxygentocarbonwhich is a weaker reducing agent .As a result, these oxides cannot be
reduced to the metallic form by heating with carbon.
SHORT ANSWER QUESTIONS
Q.1 Metals at the top of the activity series do not occur in the Free State. Explain.
Ans. Metals at the top of the activity series are highly reactive in nature and are very strong reducing agent
.They therefore, occur as oxides, sulphides and carbonates etc. and do not occur in the Free State.
Q.2What is the difference between the normal and Lewis symbol of an element.
Ans. in the normal symbol, the valence electrons are not shown while in the Lewis symbol, these are shown
either by dots or by crosses. For example, ordinary symbol of sodium is Na while its Lewis symbols Na..
Q.3What is a Thermite reaction.
Ans. It is the reduction of certain metal oxides such as MnO2, Cr2O3, Fe2O3etc by aluminum metal upon
strong heating .It is highly exothermic in nature. For example:
Fe 2O 3 +2Al →Al 2O3+2Fe +Heat
Q.4Name the alloy of
1. Aluminum
2. Lead
3. Copper
ans .1. Duralumin
2. Solder
3. Brass
Q.5Why is non-metals gases at room temperature.
Ans. In the molecular form, non-metals exist as a single molecules e.g., hydrogen, oxygen, nitrogen, carbon
dioxide etc. The attractive forces in these molecules are quits weak. Therefore exits as gases at room
temperature.
Q.6 Metals at the top of the activity series do not occur in the free state. Explain.
Ans .Metals at the top of the activity series are highly reactive in nature and are very strong reducing
agents. They therefore, occur as oxides, sulphides and carbonates etc .and do not occur in the free state.
Q.7 Name two neutral oxides.
Ans. Carbon monoxide and nitrous oxides
Q.8What is the chemical formula of rust.
Ans. Fe2O3.xH2O.
Q.9 Name the process used for the enrichment of the sulphide ore.
Ans. Froth Floatation Process.
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2
Q.10 Arrange the following in decreasing order of reactivity. Fe, Zn, Ca, Mg, Cu, Ag
Ans. Ca>Mg>Zn>Fe>Cu>Ag
Q.11 Name two metals which exits in the Free State.
Ans. Gold and Platinum
Q.12 which metal is the best conductor of electricity.
Ans. Silver
Q.13 Name two non- metal which exist in solid state and onenon-metals which exist in liquid state.
Ans. Solid state:-Sulphur and Phosphorus
Liquid state: -Bromine.
Q.14 Which metal is used in amalgams.
Ans. Mercury
Q.15 What is the name of the bond formed when a metal atom combines with the atom of non-metal.
Ans. Ionic and electrovalent bond.
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3
4. Carbon and its compounds
Important terms and conditions
 Versatility of carbon: Carbon is a non-metal and occurs in free as well combined state in nature.
 Free State: Diamond, graphite and coal.
 Combined state :
1.Solid state: All animals and plants products.
2.Liquid state: Petroleum and vegetable oil.
3.Gaseous state: In air has CO2.
 Catenation:
It combines with itself and forms a long chain.Carbon has 4 valance electrons carbon cannot form
an anion C-4 by gain of electrons. It can also not form of cations C+4 by loss of electron. It can share
its balanced electrons with other carbon atoms or atoms of non-metal and forms covalent bonding.
 Compounds of carbon: Simplest compounds of carbon are hydro carbon and simplest hydro carbon
is methane.
Classification of hydro carbon:
Saturated hydro carbon:
Compounds having single bond
Unsaturated hydro carbon:
compounds having double and triple bonds.
ALKANES
ALKENES AND ALKYNES.
Alkanes (CnH2n+2)
alkenes(CnH2n)
e.g ethane (C2H6)
alkynes. (CnH2n+2)
eg:Ehene C2H4Ethyne C2H2
Sr no
Hydro carbons
Definitions
Examples
1
Straight chain
All carbons are in form of
straight chain
Butane
2
Branched Chain
One or more carbon atoms are
attached to main straight line
Isobutane.
3.
Carbon atoms are in form of
ring and atoms bonded by single
covalent bond.
Cyclohexane.
a
Ring or cycle
hydro carbon
Saturated
b
Unsaturated
Carbon atoms are bonded by
one or more doubled covalent
bond.
Benzene.
Isomerism: The phenomenon of existence of compounds in two or more forms with same
formula but different structure.
molecular
Functional group: An atom or groups of atoms which makes a carbon compounds reactive and decide its
properties.
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4
Sr.no.
Hetero
atoms
Functional
groups
Formula of
functional
group
example
1.
Cl/Br
Halochloro/bromo
-Cl,-Br
Chloromethane(CH3Cl)
2.
oxygen
1.Alochol
-OH
Ethanol
C2H5OH
2.Aldehyde
-CHO
Methanal
HCHO
3.Ketone
>C=O
Propanone
CH3COCH3
4.Carboxylic
acid
-COOH
Ethanoic acid
CH3COOH
HOMOLOGOUS SERIES:A series of compounds in which the same functional group substitute for
hydrogen in a carbon chain, such that successive compounds differ by CH2 groups e.g CH4,C2H6,C3H8 etc.
NOMENCLATURE OF CARBON COMPOUNDS:
Prefix word root+suffix+Functional group.
CARBON COMPOUNDS:
ETHANOL: C2H5OH common name is ethyl alcohol
ETHANOIC ACID: CH3COOH.Common name is acetic acid.
ESTERIFICATION REACTION:The reaction between carboxylic acid and an alcohol in the presence of
conc. Suphuric acid to form a sweet smelling substance ester. .e.g
Conc H2SO4
CH3COOH+C2H5OH -----------→
CH3COOC2H5+H2O
Saponficationreaction :
Alkaline hydrolysis of ester produces soaps.
CH3COOC2H5+NaOH
---heat→CH3COONa+C2H5OH
Reaction with carbonates and hydrogen carbonates: reaction of ethanoic acid with carbonates or bi
carbonate evolves carbon di oxide gas.
2CH3COOH+Na2CO3
2CH3COONa+CO2+H2O
SOAP AND DETERGENT: Soap is sodium and potassium salt of long chain of carboxylic acid. They
foam lather with soft water only. Detergent are ammonium or sulphonate salts of long chain carboxylic acid
.they even remain effective in hard water and foam lather.
HOTS
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5
Q.1 Give reason for the following
(a). The element carbon forms a large no. of compounds
Ans. (a). Catenation: Carbon has the unique property of self-linking which is known catenation.
In fact, any number of carbon atoms can be linked to one another by covalent bonds. This is on account if
the stability of C-C bonds since the size of the carbon atom is quite small.
Linking of carbon with
other atoms carbon is tetravalent in nature and can readily form bond with atoms like hydrogen, oxygen,
nitrogen, sulphur etc. by electron sharing.
Q.2 what are enzymes? Name the enzymes required for the fermentation of sugarcane to
Ethanol?
Ans. Enzymes are the biocatalysts which catalyze the reactions in the living being. In the process of
fermentation of sugar into ethanol, two enzymes are used, they are invertase and zymase..
C₁₂H₂₂O₁₁ + H₂O → C₆H₁₂O₆ + C₆H₁₂O₆
C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂
Q.3 A to F are the structural formula of organic compounds?
A.
H H
│
B. H─C≡C─H
C.H
│
/
\
H─C ─ C─H
E.
H
│
│
H
HHHH
C═C
/
H
F.
│
\
D.
H
│
H─C≡C─C─H
│
H H
│ │
H─C─Br
H─C─C─H
│
│ │
H
HH
(i)Give the letters which represent the same family
(ii)Give the letters which do not represent hydrocarbons
(iii)How can C be converted into A
Ans. (i) Letter B and D represent the family of alkynes.
(ii) Letter E and F represent any hydrocarbon.
(iii)C can be converted in to A passing by hydrogen in the presence of Ni at 473K.
Q.4 (a) Why on some of compound called saturated and other unsaturated compounds?
(b) Which of these are more reactant?
(i) H
H
│ │
(ii)
H HHH
│ │ │ │
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6
H─C─C─Br
H─C─C─C─C─CC─H
│ │
│ │ │ │
H HHHHH
(c) Write the names of the compounds?
Ans. (a) The compounds in which only C─C single bond are present are called saturated Compounds these
are named because of their low reactivity. The compounds in which at least one (C═C) or (C≡C) is present
are called unsaturated compounds.
(b) Unsaturated compounds are more reactive than saturated compounds.
(c) a. Bromo ethane
b. Hex-1-yne
Q.5 Distinguish between esterification and saponification reactions of organic compounds.
Ans. In the esterification reaction an acid reacts with alcohol in the presence of conc. H₂SO₄ to
Form an ester with a pleasant or fruity smell.
CH₃COOH + C₂H₅OH → CH₃COOC₂H₅ + H₂O
Saponification is quite different from esterification because in this case an ester reacts with
to from salt of acid and alcohol.
an alkali
CH₃COOC₂H₅ + NaOH → CH₃COONa + C₂H₅OH
Q.6 (a) What is homologous series of substances?
(b) In organic compound, from alkyl group and functional group which part determines the Physical and
chemical properties?
Ans. (a) A series of similarity constituted compounds in which the members present have the Same
functional group, same chemical properties and any two successive members in a particular series differ in
their molecular formula by CH₂ group.
(b) functional group determines the physical and chemical properties of compounds.
Q.7 How do diamond and graphite differ in their structure? Is there any effect of structures on The nature of
the these?
Ans. Diamond and graphite are the two crystalline allotropic forms of carbon but they differ in Their
structure. In diamond, all the four valance electrons of carbon atoms are involved in the covalent bond
formation with the electrons of neighboring C-atom.
In graphite only three electrons participate in the bond formation while the fourth Electron is free
diamond without any free electron in a poor conductor of electricity. While Graphite with free electron
available is a good conductor.
Q.8 Why are soaps are not so effective in case of hard water?
Ans. Soaps are the sodium or potassium sales of higher fatty acids. They reacts with Ca2+ and Mg2+ ions
by present in hard water and form corresponding calcium and magnesium salts of the acids since these salts
are insoluble in water, a lot of soap is water as curdy white precipitate also known as scum.
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7
Long Answer Question
Q.1 Write chemical equation if the reaction of Ethanoic acid with :
1. Sodium
2. Sodium carbonate
3. Ethanol in the presence of conc. H2SO4.
Ans. 1.2CH3COOH + 2Na → 2CH3COONa + H2
2. 2CH2COOH + Na2CO3 → 2CH3COONa + CO2 + H2O
3.CH3COOH + C2H5OH → CH3COOC2H5 + H2O.
Q.2 Write the structural formulas and IUPAC names of all the isomers of Hexane C6H14.
Ans.1 CH3─CH2─CH2─CH2─CH2─CH3
Hexane
2.
CH3
│
CH3─CH─CH2─CH2─CH3
2-Methyl pentane
3.
CH3
│
CH3─CH─2CH─CH2─CH3
2,3 Dimethyl butane
4.
CH3 CH3
│
│
CH3-CH-CH2-CH3
2,2 Dimethyl butane
Q.3 Both carbon and Silicon belong to group 14 of the periodic table. But the tendency to exibhitcations in
the carbon is much more than in the silicon. Explain?
Ans. The size of carbon atom is small as compared to the of silicon. This is quite expected also as the
atomic size increases atom a group. Therefore C-C bond is smaller and stronger than Si-Si bond .As a
result, any of carbon atoms can be linked to each other resulting in a long number if carbon compounds.
However, this is not possible in silicon and only a few atoms can be linked by covalent bond.
Q.4 A compound ‘X’ has the molecular formula C3H6O with structural formula CH3CH2. Give its IUPAC
names can another compound have the same molecular formula? Give the structural and IUPAC names of
that compound also?
Ans. The IUPAC names of X is proposal another compound Y can also have the same molecular formula
but different structural formula.
It is
O
2
8
║
CH3-C-CH3 IUPAC Name Propanone
The compound X and Y are related to each other as functional Isomers
Q.5 Give one example each of the compound having the following functional groups. Also give their
Names?
(i) Aldehyde group
(iv) Ester group
(ii)Alcoholic group
(v) Keto group
(iii)Carboxyl group
Ans.
Functional Group
Example
IUPAC Name
CHO
HCHO
Methanal
OH
CH3OH
Methanol
COOH
HCOOH
Methanoic acid
COOR
CH3COOCH3
Methyl ethanoate
Q.6 What is meant by denatured alcohol? What is the need to denature alcohol?
Ans. Ethanol which has been made unfit for drinking purposes by adding poisonous substances like
Methanol, pyridine etc.
Need: To supply cheaper alcohol to industries and to refrain people from drinking, alcohol is Denatured by
adding poisonous substance such as methanol, pyridine etc.
Q.7. What is substitution reaction? Illustrate with example?
Ans.A reaction in which one or more hydrogen atoms of an organic compound is/are replaced by other.
Atom or group without any change in the react of the molecule is called substitution reaction.
CH4 + Cl → CH3Cl + HCl
Q.8 Write the molecular formula of
(i) an alkane (ii) an alkene (iii) an alkyne containing six carbon atoms
Ans. (i) Alkane: Put n=6 is the general formula CnH2n+2, we have C6H14
(ii) Alkene: Put n=6 is the general formula CnH2n, we have C6H12
(iii)Alkyne: Put n=6 in the general formula CnH2n-2, we have C6H10
Q.9 Give an example of each of the following
(a) A carbon containing two double bonds
(b) A molecule in which central atom is linked to three other atoms
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9
(c) An organic compound which a soluble in water.
Ans. (a) Carbon dioxide
(b) Ammonia
:Ӧ ═ C ═ Ӧ:
H─̈N─H
│
H
(c) CH3CH2OH
Q.10 (a) Name the B fatty acids whose sodium or potassium salts are present in soaps?
(b) What is scum? How is it formed?
(c) Label the hydrophilic and hydrophobic part in the following?
Ans. (a) Palm tic acid, stearic acid, and oleic acid
(b) The Ca2+ and Mg2+ ions present in hard water react with soap to form white precipitate. The White
precipitate called sucm.
2C17H35CoNa + Ca2+→ (C17H35Co)2Ca + 2Na+
(c) CH3(CH2)10CH2 ─
Hydrophobic part
OSO3-Na+
Hydrophilic part
CH3(CH2)14CH2 ─ N+(CH3)3BrHydrophobic part
Hydrophilic part
SHORT ANSWER QUESTIONS
Q.1 Why is carbon is tetravalent?
Ans .Carbon atom has 4 e- in the outermost shell. It needs 4 more e- to complete its octet Therefore, carbon
is tetravalent.
Q.2 Name a cyclic unsaturated hydrocarbon?
Ans. Benzene
Q.3 what is Petrol?
Ans. Petrol is a mixture of saturated hydrocarbon containing 7-10 C- atoms.
Q.4 what is rectified spirit?
Ans. The alcohol obtained by distillation of the mixture obtained after fermentation of molasses or sweet
fruits are called rectified spirit. It contains about 95% alcohol and 5% water.
Q.5 Name the catalyst commonly used in hydrogenation of oils to form fats?
Ans. Nickel
Q.6 what is scum?
Ans. The Ca and Mg salt of soap.
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Q.7 Name the hydrophobic and hydrophilic end of soap?
Ans. The long hydrocarbon chain which is insoluble in water is the hydrophobic end while –COO- end
which dissolve in water is the hydrophilic end.
Q.8 Why is candle flame generally yellow?
Ans. It is due to presence of sunburn carbon particles. When light fall on them, they scatter yellow color.
Q.9 An unknown compound has the smell of vinegar .Identify it.
Ans.The compound is acetic acid.
Q.10 Why is high temperature not favorable for alcoholic fermentation?
Ans. The high temperature destroys the enzymes which are needed to carry fermentation.
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1
5.Periodic classification of elements
Classification of elements: the arrangement of element in such manner that element with similar properties
are grouped together while elements with dissimilar properties are separated.
Early attempt to classify elements:
DOBEREINER’S TRIADS:
He arranged the elements with similar properties in a group of three known as triad in such a manner
that the atomic mass of the middle element was approximately the average of the other two elements
LIMITATIONS:
Only three triads were identified from the element known at that time .hence this classification was not
useful.
NEWLAND’S LAW OF OCTAVES:
He arranged the element in the order of increasing atomic masses starting with hydrogen(least atomic
mass) and ended with thorium having atomic mass 56 . According to him, the properties of every
eighth element are similar to the firstelement. It was compared to music notation sa,re ,ga ,ma, pa ,dha
,ni ,sa,and thus the name Newlands law of octaves(notes of music ).
LIMITATIONS:
1. It was applicable only for lighter element having atomic mass upto 40 amu.i.e.upto calcium .
2. He believed that only 56 elements existed in nature but later on more elements were discovered
whose properties did not fit into Newland law of octaves.
3. Some elements having different properties were grouped together like cobalt and nickel have been
placed withhalogens.
Due to above limitations, Newland law of octave was rejected
MANDELEEV’S PERIODIC TABLE:
He arranged the elements in order of increasing atomic masses, similarity in physical and chemical
properties of element. Properties of hydrides and oxides of different element were studied and elements
with similar properties were grouped together.
He classified the elements in table consisted of vertical columns called groups and horizontal rows
called periods .there were 7 groups in table and group is subdivided into subgroups A and B except
group 7 which has three sets of elements in 4th , 5th , 6th period.
LIMITATIONS OF MENDELEEV, PERIODIC TABLE:
1. Position of hydrogen was not assigned correctly.
2.
No separate position has been given to isotopes of an element.
3.
Some element having higher atomic mass is placed before the elements with lower atomic mass.
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2
MODERN PERIODIC TABLE:
Mosely modified the Mandelleve’s periodic table by taking atomic number as the fundamental property
instead of atomic mass.
Modern periodic table consists of 18 vertical columns known as group, and 7 horizontal rows known as
periods .
GROUPS:
Elements in group one is called alkali metals.
Elements in group 2 are called alkaline earth metals.
Elements in group 17 are called halogens.
Group 18 element is called inert gasses or noble gases.
Significance of group in the periodic table is that an element in a group has same number of valance
electron, valency and thus identical chemical properties.
PERIODS
1ST PERIOD – 2 elements and is called very short period.
2nd PERIOD- 8 elements and are called short period.
3rd PERIOD – 8 elements and are called short period.
4th PERIOD – 18 elements and are called long period.
5th PERIOD – 18 elements and are called long period.
6th PERIOD – 32 elements and are called very long period.
7th PERIOD- incomplete period.
The number of shell present in the element indicates the period to which it belongs.
VALENCY:
It is defined as the combing capacity of an atom of an element to acquire noble gas configuration. It is
equal to the number of electron lost, gained or shared during the formation of chemical compound.
ATOMIC SIZE / ATOMIC RADII:
It is defined as the distance from the centre of the nucleus to the outer most cell of atom .it is generally
expressed in pico meter ( pm) .
On moving down the group the atomic radii increases.
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3
Because on moving down the group a new energy shell is added which increases the distance between
the outermost electron and the nucleus . All though the nucleus charge also increases , but it is
compensated by the additional shell being added thus , increasing the size of the atom .
Across the period the atomic radii decrease. Due to the increase nuclear charge , the pull on the electron
increases and hence, they are pulled closer to the nucleus thus, decreasing the atomic size .
Oxides and its nature. Metal reacts with oxygen to form oxides by loss of electrons. These oxides on
dissolution in water from bases.
REACTIVITY OF ELEMENTS.
Down the group reactivity of metal increases as the tendency to lose electron increases due to the
increased atomic size.
Reactivity of non-metals decreases down the group because of the increased atomic size and the
tendency to gain electron decreases.
On moving across the period the reactivity first increases due to the decreased in the metallic character
and increase in nonmetallic character.
HOTS
Q.1 Why do think the noble gas are placed in a separate group?
Ans. They are present in low concentration in our atmosphere rand have stable outer configuration.
Q.2 Explain the following:
a. Hydrogen is regarded as rogue element in the periodic table.
b. Alkali metals do not form dipositive ions.
Ans.A ). Because Hydrogen resemble alkali metals in some properties and Halogen in some other
properties. Therefore it can be placed either along with alkali metals of group 1 and halogen of group 17
b. Alkali has one electron in the valence shell. By losing the electron, they acquires the stable electron
configuration if the unipositive ions. Once, they achieve the noble gas configuration, these unipositive ions
have no tendency to lose another electron to form dipositive ion. Since the energy required is so large.
Q.3 Write the electronic configuration of the following ion Cl , O, Ca, As.
Ans. The electronic configuration of element and their ions are:
Cl =2,8,7
Cl- = 2,8,8
O=2,6
O2- =2,8
Ca=2,8,8,2
Ca2+ =2,8,8
Al=2,8,3
Al3+ =2,8
Q.4 Atomic number is considered to be a more appropriate parameter than atomic mass for classification of
element in a periodic table. Why?
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Ans. The properties of an elements upon its outer electronics configuration which in turn, depends upon the
number of electrons i.e atomic number .Therefore, atomic number is a more appropriate parameter than
atomic mass.
Q.5 An atom has electronic configuration 2,8,7
a. What is the atomic number of these element.
b.To which of the following elements would it be chemically similar N(7), F(9), P(15), Ar(18).
Ans.a. The electronic configuration of the element is 2,8,7 therefore atomic number of element
2+8+7 =17
b. Since the element has 7 electron in the valence shell .It belong to the halogen family of group 17.So it is
similar to F.
Q.6 Nitrogen (At. No = 7) and Phosphorus (At. No = 15) belong to group 15 of the periodic table .Write the
electronic configuration of these 2 elements, which of these will be more electro negative .Why?
Ans.At. No
N
P
electronic configuration
17
2,5
15
2,8,5
Both these element have 5 electron in their respective valance shells and then have a high tendency to
gain 3 more electrons to form negative ion by completing their respective orbitals. Thus both these element
are electro negative. Further since atomic size increase down a group. Therefore Nhas smaller size than P
and hence is more electronegative than P.
Q.7 The position of these element A,B,C in the periodic table are shown below
Period
group16
group17
2
3
A.
B.
C.
D.
A
4
B
5
B
C
State whether C is metal or non-metal.
State whether C is more reactive or less reactive than C.
Will C be the longer or smaller in size than B.
What type of ion will be formed by element C?
Ans. a. Element of group 17 have 7 electron in their respective valance shells and these have a tendency to
complete their respective octet. Thus C which is an element of group 17 is a non-metal.
b. As we move down a group ,the atomic size increases .Therefore the force of attraction of the
nucleus for the incoming electron decreases and hence the reactivity decreases down the group. Since
element C has larger atomic size than element A , therefore C is less reactive than the element A.
c. Element B and C belong to the same period i.e 5th period . As we move from left to right in a period the
nuclear charge increases but the number of shells remains to be the same .Therefore the size decreases from
left to right then the atomic size of C is smaller than that of B.
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d. Since element C has 7 electrons in the valence shell ,therefore it has a high tendency to gain one electron
to complete its octet. Thus element C forms an atom i.e
C + e- = CQ.8 A metal M forms an oxide having the formula M2O3 .It belong to 3rd period in the modern periodic
table .Write the atomic number and valency of the metal.
Ans. The formula M2O3 indicates that the valency of M is 3. It has 3 valence electron and belong to group
15 , since it present in 3rd period , the element is Aluminum (Al). The formula of oxide is Al2O3 .
LONG ANSWER QUESTIONS
Q.1 Explain why the number of elements in the period is 8?
Ans .According to 2n2 rule, the maximum number of e- in the third period = 2×32=18.But the last shell
cannot accommodate more than 8 e- .Therefore; the number in the third period is 8.
Q.2 Lithium, Sodium and Potassium have been put in the same group on the basis of their similar chemical
properties:
a) What are those similar properties?
b) What is the usual name of this group or family?
Ans. a) Similar chemical properties of the elements, lithium, sodium and potassium are:-All these elements are metals.
-All of these have a valency of one .i.e., they are monovalent .
-All these elements react with water to form alkalis with the evolution of H2 gas.
b) These elements are collectively called alkali metals because they react with water to form alkali.
Q.3 a) An unknown element is given the given the name eka- phosphorus? What does it mean?
b) Why does not element present in a period show similar characteristics?
Ans. a) It means that the element belongs to the same group as phosphorus (Group-15) and is placed after
phosphorus .Moreover, its properties are also similar to those of phosphorus.
b) The properties of the elements are related to their electronic configuration. The element with similar
valence shell electronic configuration show similar properties. Since it changes along a period therefore, the
elements in a period differ in their characteristic.
Q.4 Calcium is an element with atomic number 20.
a) Is it a metal or non-metal?
b)Will its size be more or smaller than that of potassium?
c)Write the formula of its chloride?
Ans. The E.Configuration of Ca :-2,8,8,2
a) Since it has only two valence e-,it is present in group 2.It is a metal.
b) Both potassium and Ca are present in 4th period .Since atomic size decreases along a period
,Calcium is smaller in size.
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c) The valency of Ca is 2.The formula of its chloride is CaCl2.
Q.5Which physical and chemical properties of the elements were used by Mendeleev in creating his
periodic table ?List two observation which posed to Mendeleev’s periodic law?
Ans. The creation of Mendeleev periodic table was based upon certain physical and chemical
properties:
Physical properties: The atomic masses of the elements were taken into account and the element was
arranged in order of increasing atomic masses. The influence some of their physical properties such as
M.P,B.P, Density etc.
Chemical properties: The distribution of the elements into different group was linked with formation of
hydrides by combining with oxygen .This is linked with the valency of the elements.
The two main observations which posed challenge to Mendeleev periodic table are as follows:
a) Position of isotope: Since the isotope of an element differs in their atomic masses, they must be
assigned separate slots or position in the periodic table.
b) Anomalous position of some elements: In the Mendeleev period table, certain element with higher
atomic masses precede or placed before the elements with lower atomic masses .For ex. Ar. Is
placed before the element K.
SHORT ANSWER QUESTIONS
Q.1 Why are the member of Group1 known as alkali metals?
Ans. Because they react with water to form soluble hydroxide that are called alkali.
Q.2 on which side of the periodic table are the metal located?
Ans .Left and also in the centre of the periodic table.
Q.3Which of the following species is isoelectronic in nature?
i. Ca2+
ii. K
iii. Mg2+
iv.
S2v. ClAns.Ca2+,S-,Cl- these have 18 e-.
Q.4 Name three elements which behave as metalloid?
Ans .Arsenic, Antimony, germanium.
Q.5 Two element A and B belong to the same period .What is common in them?
Ans .They have the same number of shells.
Q.6 What is the name given to the elements present in group 17? Why are they so named?
Ans. Elements belonging to group 17 are called Halogens .The word Halogen stands for sea-salt
forming .Since most of the salts present in the sea water are chlorides, bromides, and iodide, that is why the
elements are called Halogens.
Q.7 On the basis of the periodic classification , identify each set belonging to either to group or a period:
i.
ii.
iii.
Na, Mg ,Al
Na ,K ,Rb
B,C,N
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iv.
He, Ne ,Ar
Ans. Period
Group
Period
Group
Q.8 What are the definite gaps of the atomic numbers in a group?
Ans.8, 8,18, 18,32
Q.9 What was the criteria used by Mendeleev in creating his periodic table?
Ans. Atomic masses of the elements
Q.10 Name the inert gas which has 2 electrons in the valence shell?
Ans, Helium
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CHAPTER 6 -LIFE PROCESSES
KEY CONCEPTS & GIST OF THE LESSON




Life processes – The processes that are necessary for an organism to stay alive. Eg. Nutrition, respiration, etc.
Criteria of life- (i) Growth (ii) Movement
Nutrition- The process in which an organism takes in food, utilizes it to get energy, for growth, repair and
maintenance, etc. and excretes the waste materials from the body.
Types of nutrition
1. Autotrophic nutrition(Auto =self: trophos = nourishment) E.g. Plants, Algae, blue green bacteria.
 Energy conversion- Light/Solar energy to Chemical energy
 Role off Chlorophyll- To trap the sun’s energy for photosynthesis
 Environmental Factors- (i) Carbon dioxide (ii) Water(iii) Light (iv) Temperature
 Events/ Steps of photosynthesisa)
Absorption of light energy by chlorophyll
b)
Conversion of light energy to chemical energy & Splitting of water molecule into Hydrogen
& oxygen
c)
Reduction of Carbon dioxide to Carbohydrate
 Gaseous exchange- (i) Gas used- Carbon dioxide
(ii) By product - Oxygen
 Source of raw materialsa) Carbon dioxide –Land plants- Air, Aquatic plants- Water
b) Water & Minerals - Soil
2. Heterotrophic nutrition (Hetero = others: trophos = nourishment) Eg. Animals, some plants and fungi.
 Saprophytic nutrition: Organisms feeds on dead decaying plants or animal’s material.
 Parasitic nutrition: Organisms obtain food from the body of other living organisms (host)
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 Holozoic nutrition: Organism (mostly animals) takes in whole food and then digests it into smaller
particles with enzyme.
 Steps in Holozoic nutrition
a) Ingestion: taking in of food.
b) Digestion: breaking down of complex food into simpler, absorbable form.
c) Assimilation: Utilization of digested food from the body.
d) Egestion: Removing undigested food from the body
 Nutrition in human beings
 Alimentary canal-
Mouth → Oesophagus → Stomach → Small intestine → Large intestine →
Rectum → Anus
Organ
Gland
Enzyme/Juice
Function
Mouth
Salivary glands
Salivary Amylase
Converts starch into sugar
Stomach
Gastric glands
Gastric juice(i) Hydrochloric
acid
(a) Kills harmful bacteria that
→
enters with the food.
(a) Makes the medium acidic
for the action of Pepsin
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Digests proteins
Small intestine
1) Liver
(ii) Pepsin
→
(iii) Mucus
→
Protects the inner lining of the stomach
from the corrosive action of
Hydrochloric acid.
(i) Bile juice
→
(a) Makes the medium Alkaline
for the action of Pancreatic
enzymes.
(b) Breaks down large fat
molecules into smaller globules
so that enzymes can act upon
them.
2) Pancreas
(ii) Pancreatic
Juice



Amylase →
Trypsin →
Lipase →
Converts Carbohydrates to glucose
Converts Proteins to Amino acids
Converts Fats into Fatty acids &
Glycerol
 Peristaltic movements- Rhythmic contraction of muscles of the lining of Alimentary canal to push the
food forward.
 Sphincter muscle- Helps in the exit of food from the stomach.
 Villi and microvilli- Small finger like projections on the walls ofa) Small intestine- To increase the surface area for the absorption of food.
b) Large intestine- For absorption of water.
Respiration
 The process by which digested food is broken down with the help of Oxygen to release energy.
 Types ofrespiration- (i) Aerobic respiration (ii) Anaerobic respiration
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Aerobic respiration
Anaerobic respiration
1. Takes place in presence of Oxygen.
1. Takes place in absence of Oxygen.
2. End products- Carbon dioxide & Water
2. End products- Ethanol & Carbon dioxide
3. More energy is released.
3. Less energy is released.
4. Takes place in Cytoplasm & Mitochondria
4. Takes place in only in Cytoplasm.
5. Complete oxidation of glucose takes place.
5. Incomplete oxidation of glucose takes place.
6. It occurs in most organisms.
6. It occurs in certain bacteria, yeast & certain
tissues of higher organisms. E.g. In humans
during vigorous exercise, when the demand for
Oxygen is more than the supply, muscle cells
respire anaerobically for some time.
7. EquationGlucose → Pyruvate → CO2 + H2O + Energy
7. EquationIn YeastGlucose→ Pyruvate→ Ethanol + H2O + Energy
In muscle cells Glucose→ Pyruvate→ Lactic acid + Energy
 Some common features of Respiratory organs(i) Large
surface area- for greater rate of diffusion of respiratory gases.
(ii) Thin permeable walls
– to ensure easy diffusion & exchange of gases.
(iii) Extensive blood supply- Respiratory
organs are richly supplied with blood vessels for quick transport of gases.
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Mind Map
 Gaseous exchange in plants-
 Process – Diffusion
 Direction of diffusion depends oni. Environmental conditions
ii. Requirement of the plant.

 Day time- Carbon dioxide given out during respiration is used for photosynthesis. Therefore only
Oxygen is released, which is a major activity during the day.
 Night time – Only respiration takes place. Therefore only Carbon dioxide is released, which is a
major activity during the night.
Gaseous exchange in animals Terrestrial animals- take Oxygen from the atmosphere.
 Aquatic animals- take Oxygen dissolved in water. (Oxygen content is low in water, therefore they
breathe faster.
 Human Respiratory systemExternal
nostrils → Nasal cavity → Trachea→ Bronchi → Bronchioles →Alveoli
 Rings of cartilage present in the throat ensure that the trachea (air passage) does not collapse when
there is less air in it.
 Lungs –
i. Present in the thoracic cavity.
ii. They are spongy, elastic bags consisting of Bronchi,
iii. Bronchioles and Alveoli
Respiration occurs in two phases(i) External Respiration- Breathing, which is a mechanical process.
Internal Respiration - Cellular respiration
 Mechanism of breathing – It includes : (i)Inhalation (ii) Exhalation
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3
(ii)
 Exchange of gases Unicellular organisms- By Diffusion
 Animals- As the body size is large, diffusion alone is not enough.

Respiratory pigments also required.

Respiratory pigment in human beings is Haemoglobin,

It has very high affinity for Oxygen.

Carbon dioxide is more soluble in water than Oxygen, so it Gets
dissolves in blood and is thus transported.
Transportation

Transportation in human beingsBlood- (i) It is a fluid connective tissue.
(ii) Components- (1) Fluid medium- Plasma
(2) Red blood corpuscles
(3) White blood corpuscles
(4) Platelets suspended in plasma
(iii) Plasma transports food, Oxygen, Carbon dioxide,
Nitrogenous wastes, etc.

Functions of blood- (i) Transport of respiratory gases.
(ii) Transport of nutrients.
(iii) Transport of waste products.
(iv) Defence against infection

Blood vessels- (i) Arteries (ii) Veins (iii) Capillaries
Arteries
Veins
1. Thick walled.
1. Thin walled.
2. Deep seated.
2. Superficial.
3. Carry blood away from the heart.
3. Carry blood to the heart.
4. Carry Oxygenated blood.
4. Carry Deoxygenated blood.
5. Valves absent.
5. Valves present
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
Heart- (i) It is a muscular organ, which works as a pump in the circulatory system.
(ii) It has two sides, which are separated by a partition so that the oxygenated and
Deoxygenated blood does not get mixed up.
(iii) It has four chambersTwo upper chambers called Atria.
Two lower chambers called Ventricles.
 Working of heartLeft side- (i) Left atrium relaxes & the Oxygenated blood enters in it from
the lungs through the pulmonary vein.
(ii) Left atrium contracts & the blood enters the left ventricle
through the valve.
(iii) Left Ventricle contracts and the blood is pumped into the
largest artery ‘Aorta’ and is carried to all parts of the body.
Right side- (i) Right atrium relaxes & the deoxygenated blood from the body enters it
through superior and inferior Vena cava.
(ii) Right atrium contracts & the blood enters the right Ventricle through
the valve.
(iii) Right Ventricle contracts and the blood is pumped into the Pulmonary
artery and is carried to lungs.




Valves- Unidirectional to prevent the backward flow of blood.
Pulmonary vein is the only vein that carries Oxygenated blood.
Pulmonary artery is the only artery that carries Deoxygenated blood.
Double circulation in man- because the blood passes through the heart twice in one complete cycle of
the circulation.
 Capillaries- (i) Form the connection between arteries & veins
(ii) Walls are one cell thick only for easy exchange of blood.
 Platelets- Plug the leaks of arteries and veins by clotting the blood.
 Lymph- Extracellular fluid similar to plasma but colourless with lesser protein.
 Function of lymph- (i) Transportation of digested & absorbed fats from
the small intestine.
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(ii) Drains excess fluid from the intercellular spaces
back in the blood.
 Higher animals- E.g., birds, mammals.
 Oxygenated blood & Deoxygenated blood are completely separate for efficient Oxygen supply.
 This is to fulfil higher energy needs and to maintain body temperature (warm blooded animals).
 Amphibians & reptiles- have 3 chambered heat where little mixing of Oxygenated blood & Deoxygenated
blood takes place. Therefore their body temperature varies with the temperature of the environment. (cold
blooded animals)
 Transportation in plants Plants need less energy because they do not move and therefore have a slow transport system
 Transport of water Takes place by xylem tissue present in roots, stem, and leaves and is therefore interconnected.
 Root cells take up ions from the soil, which creates a concentration difference between root and soil. Column
of water therefore rises upwards.
 In very tall plants- transpiration creates a suction pressure, which pulls the water upwards.
 Importance of transpiration
Helps in upward movement of water in plants.

It regulates the temperature in plants.
 Transport of food
Takes place by phloem tissue.

Movement of prepared food in plants is called translocation.
Excretion
 The biological process of removal of nitrogenous metabolic wastes in living organisms.
 Excretion in human beings Organs of excretory system(i) Kidneys
(iii) Urinary bladder
(ii) Ureters
(iv) Urethra
 Kidneys
Two in number

Bean shaped

Present in abdomen on either side of the backbone

Functional unit of kidney is nephron.
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6
 Glomerulus- Group of capillaries (cluster) present in Bowman’s
capsule
to receive blood from renal artery and filters it.
 Bowman’s capsule- Cup shaped structure, which contains glomerulus.
 Convoluted tubule- is long and reabsorbs vital nutrients like glucose, amino acids, salts,
urea and water.
Vital functions of kidneys- (a) Filtration & removal of Nitrogenous wastes
(b) Reabsorption of vital nutrients
 Ureters- Transport the urine formed in the kidneys to the urinary bladder.
 Urinary bladder- Muscular bag like structure to store urine.
 Urethra- Helps in removal of urine when the Urinary bladder is full.
 Excretion in plants Gaseous wastes- CO2in respiration & O2 in photosynthesis are removed by the process of diffusion.
 Excess water- is removed by transpiration.
 Other wastes- (i) Stored in cellular vacuoles or in leaves, which fall off or as
gums,
resins, etc. in old xylem.
HOTS QUESTIONS (SOLVED / UNSOLVED)
Q1. Why is it necessary to separate oxygenated and deoxygenated blood in mammals and birds?
Ans. The mammals and birds are warm-blooded animals which have high energy needs because they constantly
require energy to maintain their body temperature. It is necessary to separate oxygenated blood and deoxygenated
blood in mammals and birds because such a separation allows a highly efficient supply of oxygen to the body cells
which is required for producing a lot of energy needed by them.
Q2. How is small intestine designed to absorb digested food?
Ans. The inner surface of small intestine has millions of tiny, finger like projections called Villi. The presence of villi
gives the inner walls of the small intestine a very large surface area. The large inner surface area of small intestine
helps in the rapid absorption of the digested food.
LIFE PROCESSES
ORAL QUESTIONS
1.
Do plants also need oxygen?
2.
How does food passes through alimentary canal?
3.
What regulate the exit of food from the stomach into small intestine?
4.
In which part of the alimentary canal food is completely digested absorbed?
5.
In which cell organelle breakdown of pyruvate takes place using oxygen?
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7
6.
Which structures stop backward flow of blood in atria and ventricles?
7.
The filtered urine is collected in which part of nephron?
8.
Which part of the plant excretes some waste substances into the soil?
9.
Name the process used to remove urea from the blood.
10.
The process by which evaporation of water from the plants mainly through the stomata.
SOLVED QUESTIONS
(1) Due to availability of less water, how does the plant cope up with lack of
water in desert conditions?
(2) After a vigorous exercise, you may experience cramps in your leg
muscles. Why does this happen?
(3) What will happen if carbon monoxide combines with haemoglobin?
(4) Food moves down the gut by peristalsis. Which region of brain controls
peristalsis?
(5) Name the pigment present in plants, which can absorb solar energy.
(6) Name the respiratory organs of (i) fish (ii) mosquito (iii) earthworm
(7) Which of the four chambers of the human heart has the thickest muscular
walls?
(8) What will be the outcome if a farmer floods his field everyday?
(9) Which part of visible spectrum is absorbed by chlorophyll pigments?
(10) How does respiration in plants differ from that in animals?
(11) Name the cartilaginous flap which closes the glottis to check the entry of
food into it during swallowing.
(12) Which equipment is used to facilitate breathing during serious breathing
problems?
(13) Chloroplast are called energy convertors. Explain.
(14) Why is the rate if breathing much faster in aquatic organisms than those of
terrestrial organisms?
(15) Why are glomeruli considered as dialysis bags?
(16) Autotrophs synthesise food for the living world. Justify this statement in one
sentence only interconnecting autotrophs and heterotrophs.
(17)Veins and arteries carry blood. Which of these carry blood?
a) Away from the heart?
b) Back to the heart?
(18) Which of the organs perform the following functions in humans?
1. Absorption of food.
2. Absorption of water
(19) Name the areas in a woody stem through which respiratory exchange of gases
take place.
(20) Tooth enamel is one of the hardest substances in our body. How does it
undergo damage due to eating chocolates and sweets?
(21) A certain tissue in a green plant somehow get blocked and the leaves wilted.
What was the tissue that got blocked?
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8
(22) Write one feature which is common to each of the following pairs of the
term/organs.
i) glycogen and starch ii) chlorophyll and haemoglobin
iii) gills and lungs iv) arteries and veins.
(23) Why doesn’t the lungs collapse even after forceful expiration?
(24) The two openings of the pharynx, one leading to trachea and the other
leading to oesophagus, lie very close to each other. Yet food we swallow
normally does not enter into our trachea. Why?
(25) How would it affect the digestion of proteins and carbohydrates if the
duodenum of man if there is a blockade in the pancreatic duct?
(26) What do you mean by double circulation of blood?
(27) “If there were no algae there would be no fish in the sea”. Comment.
(28)Write the functions of the following in the digestive process:
(i) Bile
(ii) Bicarbonate secreted by the duodenal wall.
(iii) Pancreatic amylase.
(29) Why is the process of diffusion insufficient to meet the oxygen requirement
of human beings?
(30) Draw a diagram of human alimentary canal showing duodenum, small
intestine, liver and pancreas.
(31) Draw a diagram of the human urinary system and label in it.
a. Kidney
b. Ureter
c. Urinary Bladder
d. Urethra
ANSWERS
Ans-1) They open their stomata at night and stomata remain closed during day time,
to conserve moisture.
Ans-2) The sudden build up of lactic acid in our muscles during vigorous,
exercise, causes muscular cramps in our leg muscles.
Ans-3) If the haemoglobin binds with carbon monoxide strongly, the oxygen will not
be carried with blood leading to death of the organism.
Ans-4) Medulla of hind brain.
Ans-5) Chlorophyll.
Ans-6) Fish - gills
Mosquito – Trachea (air tubes)
Earthworm – moist skin
Ans-7) Right ventricle.
Ans-8) Respiration of plants will be affected because the oxygen present in the
interspaces of the soil will be replaced by water.
Ans-9) Blue and Red light
Ans-10) In plants, all parts like the root, stem, leaves, etc., perform respiration
individually., while in animals, either the general body surface or specific organs like
the skin, gills, lungs, etc., are involved in respiration. The rate of respiration is much
slower in plants than in animals. Unlike animals, there is little transport of gases from
one part of the plant to another.
Ans-11) Epiglottis
Ans-12) Ventilator
Ans-13) Chloroplasts are called energy convertors because they trap the solar energy
and convert it into chemical energy.
Ans-14) The aquatic organisms obtain oxygen dissolved in water. As compared to air,
the availability of oxygen in water is fairly low. Hence, the aquatic organisms have to
breathe faster as compared to the terrestrial organisms.
Ans-15) The main function performed by the glomeruli is selective filtration. They
filter small molecules containing glucose, salts, urea, and liquid serum. Etc. The large
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molecules such as proteins remain in blood. Thus, glomeruli of the kidneys function
as dialysis bags.
Ans-16) The food producers are autotrophs and all the heterotrophs consume the food
produced by the autotrophs directly or indirectly.
Ans-17) a) Arteries carry blood away from the heart.
b) Veins carry blood back to the heart.
Ans-18)
1. Absorption of food takes place in small intestine.
2. Large intestine
Ans-19) In woody stem, the bark has lenticels for gaseous exchange.
Ans-20) The acid is formed in the mouth after a sugary food (chocolates and sweet)
has been taken. This acid lowers the pH in the mouth. Tooth decay starts when the pH
of acid formed in the mouth falls below 5.5. This is because then the acid becomes
strong enough to attack the enamel of our teeth and corrode it.
Ans-21) The tissue that got blocked may be xylem. It is through the xylem that water
and minerals absorbed by roots from the soil are transported to the leaves and other
parts of the plant. So, if xylem is blocked, the leaves will not get the nourishment and
will get wilted.
Ans-22)
i) Carbohydrate (food)
ii) Pigments.
iii) Respiratory organs.
iv) Blood vessels.
Ans-23) Even after forceful expiration to the maximum capacity, some amount of air
remains in the lungs, known as residual volume. So, the lungs doesn’t collapse even
after forceful expiration.
Ans-24) The food does not enter into trachea because during swallowing, the aperture
leading to trachea (glottis) gets covered by a cartilaginous flap called epiglottis and
the food has no other passage except going into the oesophagus.
Ans-25) Duodenum is the region where the pancreatic juice secreted by the pancreas
enters. The enzymes pancreatic amylase and trypsin helps in the digestion of
carbohydrates and proteins. Thus, if there is a blockade, the digestion of
carbohydrates and proteins gets affected.
Ans-26) Blood passes through the heart twice for each cycle of the body.
Ans-27) Algae produce O2 as a result of photosynthesis. This oxygen is utilised by the
fishes in the sea for carrying out respiration. If there were no algae, no oxygen would
have been produced. Thus, fishes might have died.
Ans-28)
1. Bile: It is secreted by the gall bladder and it emulsifies the fats into the
smaller droplets for their easy digestion.
2. It provides alkaline medium in the duodenum which is needed for the action of
pancreatic enzymes of different food components for their digestion.
3. Pancreatic amylase enzyme digests starch and changes it into maltose.
Ans-29) The process of diffusion for carrying O2 to all parts of the body is not
sufficient for larger multicellular organisms like human beings. Hence, respiratory
pigment haemoglobin takes up oxygen from the air and carry it to all the parts of our
body through blood.
Ans-30) Textbook Page No. 99, Figure 6.6
Ans-31) Figure 6.13 Page 110 NCERT
5
0
PUZZLES
1.
Across
2. Aerial part which eliminates waste from the plant body
4. Unicellular plant that carryout fermentation.
Down
1. Transports oxygen in the body.
3. Carry impure blood.
4
1
2
2.
3
Across
1. Help in respiration in water.
3. Removed through urine.
Down
2. Help to breath in air
3. The process by nitrogenous waste is removed.
4. Organism that takes in food with the help of pseudopodia.
1
2
3
4
5
1
5
Label The Diagram Of Respiratory System
 Cross word puzzle- Circulatory system
1
2
3
4
5
6
7
8
9
5
2
10
11
Clues for solving the cross word puzzle
ACROSS
DOWN
3. The only vein that carries
oxygenated blood to the heart
4. The organ which beats
continously to act as a pump for
the transport of blood.
5. The number of chambers in the
human heart.
6. A doctor uses this instrument to
amplify the sound of the heart.
8. The two upper chambers of the
heart.
9. The heart is located on this side
of the chest cavity.
10. The only artery that carries
deoxygenated blood from the
heart.
11. They form the connection
between the arteries and veins
1. The number of heart beats per
minute.
2. The two lower chambers of the
heart.
7. The heart is roughly the size of
your ______.
5
3
Photosynthesis – Crossword puzzle
Across
Down
1 A plant pigment that absorbs sunlight. (11)
2 The process by which plants and some bacteria use
the energy from sunlight to produce sugar. (14)
4 The links between the energy that carnivores get
from eating to the energy captured by
photosynthesis. (4,5)
3 Part of the plant where photosynthesis generally
occurs. (6)
7 Chlorophyll absorbs every color of sunlight
except this. (5)
5 A compound needed for photosynthesis. (5)
6 An animal that eats plants. (9)
8 A compound needed for photosynthesis. (6,7)
9 A by-product of photosynthesis. (6)
10 The product of photosynthesis. (5)
10 Number of molecules of oxygen produced along
with one molecule of sugar. (3)
5
4
CHAPTER 7 – CONTROL & COORDINATION
KEY CONCEPTS & GIST OF THE LESSON
 Coordination-The working together of various organs of the body of an organism in a proper manner to
produce appropriate reaction to a stimulus is called coordination.
 Stimulus- The changes in the environment to which an organism responds and reacts is called Stimulus
 Control & coordination in animals- takes place by (i) Nervous system & (ii) Endocrine system
 Nervous system
Stimulus → Receptor organ → Sensory nerve → Brain/Spinal cord
↓
Response ← Effecter organ ← Motor nerve
 Endocrine system
Stimulus → Endocrine organ → Secrete hormone → Hormone in blood
↓
Response ← Target organ
 Parts of the Nervous system – (i) Brain (ii) Spinal cord (iii) Nerves (Neurons)
 A Neuron is the structural & functional unit of Nervous system
 Parts of a neuron- (i) Dendrites (ii) Cell body (iii) Axon
 Synapse- Space/junction between two adjacent nerves is called Synapse.
 Transmission of impulse – (i) By Electric impulse (inside the neuron).
(ii) In the form of chemicals (At synapse)
 Reflex action- Spontaneous, involuntary and automatic response to a stimulus to protect us from harmful
situations. Eg. On touching a hot object unknowingly we instantly withdraw our hand.
 Reflex arc - The pathway of the reflex action is called Reflex arc.
Stimulus → Receptor organ → Sensory nerve → Spinal cord →Effector organ→ Response
1. Which are the systems involved in the control and co-ordination in animals?
Important Questions
5
5
The systems involved in the control and co-ordination in animals are the Nervous system, Muscular system and
Endocrine system.
2. Name the receptors of taste and smell.
The receptor of taste is Gustatory receptor and that of smell is Olfactory receptor.
3. What is a nerve impulse?
The information passing through a neuron in the form of electrical and chemical signals is known as a Nerve Impulse.
4. How does a nerve impulse travel through the body?
The information acquired at the dendritic tip of a nerve cell sets off a chemical reaction that creates an electrical
impulse. This impulse travels from the dendrite to the cell body and then along the axon to its end. At the end of the
axon the electrical impulse sets off the release of some chemicals. These chemicals cross the gap or synapse and start
a similar electrical impulse in a dendrite of the next neuron. A similar synapse finally allows the delivery of such
impulse from neurons to other cells such as muscles or glands.
5. What is a synapse?
A Synapse is a gap between two neurons.
6. What happens at a synapse between two neurons?
At the end of the axon the electrical impulse sets off the release of some chemicals. These chemicals cross the gap or
synapse and start a similar electrical impulse in a dendrite of the next neuron.
7. What is reflex action? Give examples.
Reflex action is a quick involuntary response to a stimulus by an effector.
E.g.:
i. withdrawing our hand from a hot object.
ii. Closing the eye when a moving object approaches the eye on a collision-course.
iii. Blinking the eyelids when a moving object approaches the eye
iv. Knee-jerk reflex.
8. What is the difference between a reflex action and walking?
Reflex action is an involuntary action whereas walking is a voluntary action.
9. Draw the structure of a neuron and explain its functions.
5
6
Neurons are specialized for conducting information via electrical impulses from one part of the body to the other.
There are three types of neurons:
Sensory neurons: Conducts nerve impulses from sense organs to the brain and spinal cord.
Motor neurons: Conducts impulses from brain and spinal cord to the effectors, i.e. muscles and glands.
Relay neurons: Between the sensory neurons and motor neurons.
10. Draw the neuro-muscular junction and label its parts.
11. Draw a labelled diagram of Brain.
12. Which part of the brain maintains posture and equilibrium of the body?
5
7
Cerebellum maintains posture and equilibrium of the body.
13. Write the functions of the following parts:
i. Fore-brain
ii. Cerebellum
iii. Medulla
i. Fore-brain is the main thinking part of the brain. It has regions which receive sensory impulses from various
receptors. Separate areas of the fore-brain are specialized for hearing, smell, sight and so on. There are association
areas where sensory information is interpreted by putting it together with the information from other receptors as well
as with the information already stored in the memory of the brain. There are centers for motor areas for all muscles.
Information about how to respond to the stimuli is passed on to these motor areas.
ii. Cerebellum is responsible for precision of voluntary actions and maintaining posture and balance of the body.
iii. Medulla controls the involuntary actions including salivation, vomiting, blood pressure, etc.
15. Draw a labelled diagram of a Reflex arc.
16. How do we detect the smell of agarbathi or incense stick?
The olfactory receptors in the nose detect smell by sending nerve impulses to the olfactory centre of the brain.
17. What is the role of the brain in reflex action?
Reflex actions take place without the conscious involvement of the brain. But some of these involuntary responses are
controlled by the mid-brain and hind-brain. In spinal reflexes, quick responses are given but the information is sent to
the brain.
18. How are the brain and spinal cord protected?
The brain is protected by the bony box – Cranium of the skull. The spinal cord is protected by the vertebral column.
In addition to this, the brain and spinal cord are surrounded by membranes (meninges) which form a fluid filled
around the brain. This provides further shock absorption.
5
8
19. What are different parts of human brain?
Fore brain
Mid brain
Hind brain
(i) Cerebrum
Connects Fore brain & Hind brain
(ii) Thalamus
(iii) Hypothallamus
(i) Cerebellum
(ii) Pons
(iii) Medulla oblongata
 Fore brainCerebrum- (i) Main thinking and largest part of the brain.
(ii) It has 3 main areasa. Sensory area- to receive impulses from sense organs via Receptors
b. Motor area- control voluntary movements.
c. Association areas- Reasoning, learning & intelligence.
Thalamus – It relays sensory information to the Cerebrum
Hypothallamus- It forms the link between Nervous system & Endocrine system
Mid brain- It connects fore brain and Hind brain. Controls reflex of eyes & ears
Hind brain-Cerebellum – Controls & coordinates muscular movements, maintaining body posture and
equilibrium.
Pons- Acts as a bridge between brain & spinal cord
Medulla oblongata- Controls involuntary actions like blood pressure, salivation, vomiting, etc.
20. What protects the brain and spinal cord?
(i) Bony outer covering: skull for the brain & vertebral column for the spinal cord.
(ii) Cerebrospinal fluid present in between the three membranes.
21. How nervous tissue acts?
Information → Nervous tissue → Brain Muscles → Causes action
22. Give the path of nerve impulse.
Nerve impulse → Muscle cell → Changes shape due to special proteins
↓
Action caused ← shorter form of muscles ← Change shape & arrangement of cell

Chemical communication by hormones- (advantages)
(i) Electrical impulses have their limitations because they reach only those cells connected to the
nervous tissue.
(ii) Also the nerve cells cannot generate & transmit impulses continuously.
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9
(iii) Electrical communication is slower.
Hormones- (i) Chemical messengers secreted by endocrine glands
(ii) Are secreted in small amounts & may act in nearby places or distant places.

(iii) Do not take part in the reaction & are destroyed immediately.

Difference between Endocrine glands & Exocrine glands
S. No.
Endocrine glands
Exocrine glands
1.
Ducts absent
Ducts present
2.
Secrete hormones
Secrete enzymes
3.
Secreted in blood
Secreted in ducts of glands
4.
Situated away from the site of action
Situated near the site of action
Some glands which act as both endocrine & exocrine (Heterocrine)
Gland
Endocrine function
Exocrine function
Pancreas
Produces insulin & Glucagon
hormone.
Produces digestive enzyme. (pancreatic
amylase)
Testes
Produces hormone Testosterone
Produces male gametes (reproductive cells)
Ovaries
Produces hormone Oestrogen
Produces female gametes (reproductive cells)
Endocrine System of
Human
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0
Important Endocrine glands, the hormone they secrete & their function
Endocrine gland
Pituitary gland
Hormone
Growth hormone
Function
Body growth, development of bones & muscles
(If excess- Gigantism)
(If less- Dwarfism)
Thyroid gland
Thyroxine
Regulates carbohydrate, protein & fat metabolism( If
less- Goitre_
Adrenal Gland
Glucocorticoids
&Aldosteron,Adrenalin&
Noradrenalin
Regulates metabolism and acts as neurotransmitters
Pancreas
Produces insulin &
Glucagon hormone
Regulates blood sugar levels (if less diabetes is
caused)
Testes in males
Produces hormone
Testosterone
Development of secondary male characters like deep
voice, beard, etc.
Ovaries in
females
Produces hormone
Oestrogen
Development of secondary female characters like
mammary glands, menstrual cycle, maintenance of
pregnancy.
.
EFFECT OF AUXIN ON PLANT
CELL
6
1
THIGMONASTY
6
2
Coordination in plants
Only chemical coordination is present in plants.
 Tropic movements- The movements of plants in the direction of stimulus (positive) or away from it
(negative) are called tropic movements. E.g. Phototropism, Geotropism. Chemotropism
 Nastic movements- Movements of plants independent of stimuli are called nastic movements. E.g.Touch me not plant leaves close when touched.
 Plant hormones (Phytohormones)Examples1. Auxins- Help in growth of root & shoot tips.
2. Gibberellins- Help in vegetative growth
3. Cytokinins- Promote cell division
4. Abscissic acid - Inhibits growth & causes wilting (falling) of leaves
7. CONTROL AND CO - ORDINATION
HOTS QUESTIONS (SOLVED / UNSOLVED)
Q1. Which hormone:
1. Prepares the body for action?
2. Controls the amount of sugar (glucose) in blood?
3. Brings about changes in boys at puberty?
4. Brings about changes in girls at puberty?
Ans. a) Adrenaline
c) Testosterone
b) Insulin
d) Oestrogen
Q2. i) Name the hormone produced by thyroid gland.
ii Which mineral is necessary for the synthesis of the above hormone?
iii Name the disease suffer from the deficiency of this mineral.
iv Write the function of the above hormones?
Q3. What is chemotropism? Give one example of chemotropism.
ORAL QUESTIONS
1.
What is the basic unit of nervous system?
6
3
2.
How do neuron conduct message from brain to other parts?
3.
What do you mean by CNS?
4.
What are its main parts?
5.
Which part controls reflex action?
6.
What are endocrine glands?
7.
What is the secretion of endocrine gland called?
8.
Name a gland of human body which secretes both enzymes and hormone.
9.
Which plant hormone helps in cell division?
10.
Which hormones help on stem elongation?
HOT QUESTIONS
Q.1) On touching a hot plate, you suddenly withdraw your hand. Which category of
neurons became active first and which one next?
Q.2) Give one example of plant part.
a. Which is positively hydrotropic as well as positively geotropic.
b. Which is positively phototropic but negatively geotropic.
Q.3) What name is given to the microscopic gap between two adjacent neurons?
Q.4) If we step on something sharp accidently we move our foot away at once .what is
this type of response known as?
Q.5) A part of the hind brain makes possible activities like walking, skating, riding a
bicycle and picking up a pencil.name this part of the hind brain.
Q.6) The neck of a person appears to be swollen.
a. Name the disease this person suffering from.
b. Name the mineral whose deficiency in the diet causes this disease.
Q.7) Name the plant hormone:
(a) which inhibits growth and causes wilting of leaves.
(b) which promotes cell division.
Q.8) Taking the example of heart beat, justify the antagonistic action of the
sympathetic and the parasympathetic nerves.
Q.9) Why is abscisic acid known as stress hormone in plants?
Q.10) Name the part of neuron
(a) where information is acquired.
(b) through which information travels as an electrical impulse.
Q.11) How does the plant shoot bends, when the plant is placed in a room having only
one open window?
Q.12) Who transmits nerve impulse across the synapse?
Q.13) Give a reason to explain why
(a) adrenaline helps in dealing emergency situations?
(b) secretions of growth hormone should be specific in the human body?
Q.14) Why do leaves drop off seasonally?
Q.15) Give reason why endocrine glands release their secretions into the blood?
ANSWERS
Ans.1) On touching a hot plate, first the sensory neurons are activated, which take the
information to the brain or the spinal cord. Next, the motor neurons become active
and bring the impulses from the brain to the muscles. In receiving these impulses, the
muscles contract, and the hand is immediately removed from the hot plate.
6
4
Ans.2) a. roots
b. stem
Ans.3) Synapse
Ans.4) Reflex action
Ans.5) Cerebellum
Ans.6) a. Goitre
b. Iodine
Ans.7) a. Abscisic acid.
b. Cytokinins.
Ans.8) Sympathetic system increases contraction and rhythm and parasympathetic
system decreases contraction and rhythm with respect to heart beat.
Ans.9) Abscisic acid in a plant hormone which inhibits growth. Its effects include
wilting of leaves.
Ans.10) a. Dendrite
b. Axon
Ans.11) When the plant is placed in such a room that has only one open window, the
shoot of the plant bends towards the direction of light. Plant hormone auxin is formed
that diffuses towards the shady side of the shoot and stimulates the cells to live longer
on the side of the shoot which is away from light. In this way the shoot bends towards
the light.
Ans.12) Neurotransmitters.
Ans.13) a. Adrenaline increases the heart beat and breathing rate which results in the
supply of more oxygen to muscles. It reduces the blood to the digestive system and
skin, as a result the blood is further diverted to skeletal muscles. All these responses
together prepare the body to deal with the emergency situations.
b. If growth hormones is secreted in excess during childhood then it leads to
gigantism while the less secretion of this hormone during childhood causes dwarfism.
Ans.14) The leaves drop off seasonally as they stop producing auxins, which normally
prevents the formation of abscission zone that cuts off nutrients and water supply to
leaves.
Ans.15) Endocrine glands are ductless glands and their products have to act at a
distant site.
Therefore, they release their secretions into the blood.
QUIZ
1.
Which system of our body is made of organised network for conducting information in the body?
2.
Which part of the neuron receives information?
3.
What is the name of the neuron which remains between the sensory neuron and the motor neuron?
Where is it located?
4.
Which part of the brain helps us to do activities like riding a cycle and walking in a straight line?
5.
What are two major types of muscles we have?
6.
What causes change in leave of ‘touch me not’ plant?
6
5
7.
Which hormone helps us to prepare to combat adverse condition?
8.
Name a female sex organ which produces gametes as well as female hormone.
CROSS WORD PUZZLE: NERVOUS SYSTEM
Clues
ACROSS
1. Composed of the brain and spinal cord (3 words).
8. Contains photoreceptors; on the inner posterior portion of eye.
9. "Inside the mouth"
11. Electrical brain activity recorded with scalp or brain electrodes
(abbreviation).
13. Necessary for hearin
17. Neurotransmitter in brain, spinal cord and peripheral nervous system
(abbreviation).
18. Outermost layer of meninges.
19. Neurotransmitter lacking in patients with Parkinson's disease.
21. Supportive cells of the nervous system; "glue".
22. Nerve cell.
23. Photoreceptor that is not used for color vision.
6
6
24. Photoreceptor that is used for color vision.
26. The sense of hearing.
29. Opposite of "Yes"
30. Junction between two neurons.
DOWN
1. In the brain, it is the outermost layer of the gray matter.
2. The fifth cranial nerve.
3. The middle layer of the meninges.
4. The part of the cell containing chromosomes.
5. Period of sleep when dreams occur (abbreviation).
6. The second cranial nerve.
7. Fat-like substance that surrounds some axons.
10. The first cranial nerve.
12. Fluid that fills the ventricles (abbreviation).
14. Part of neuron that takes information TO the cell body.
16. Short for "mother".
18. Electrical brain activity between 2 and 4 Hz.
20. Part of neuron that takes information AWAY from the cell body.
22. A short written letter.
24. Abbreviation for 1 across.
25. Organ for vision.
27. Opposite of "off".
28. Opposite of "yes".
ANSWERS: CROSS WORD PUZZLE: NERVOUS SYSTEM
6
7
SUMMATIVE ASSESSMENT I
TIME: 3-31/2 HOURS
M.M: 80
General Instructions:
General Instructions:
1. The question paper comprises of two sections, A and B you are to attempt both the sections.
2. All questions are compulsory.
3. There is no overall choice. However, internal choice has been provided in all the three questions of five
marks category. Only one option in such question is to be attempted.
4. All questions to section A and all questions of section B are to be attempted separately.
5. Question numbers 1 to 3 in section A are mark questions. These are to be answered in one word or one
sentence.
6. Question numbers 4 to 7 are two marks questions, to be answered in about 30 words.
7. Question number 8 to 19 is three mark questions, to be answered in about 50 words.
8. Question number 20 to 24 are five mark questions, to be answered in about 70 words.
9. Question numbers 25 to 42 in section B are multiple choice questions based on practical skills. Each
question is a one mark question. You are choosing one most appropriate response out of the four provided to
you.
10. An addition 15 minutes time has been allotted to read this question paper only.
Questions:
1] A non-metal X exists in two different forms Y and Z. Y is the hardest natural substance, whereas [Marks:1
Z is a good conductor of electricity. Identify Y and Z.
]
2] What is the minimum resistance which can be made using five resistors each of 1/5
6
8
?
[Marks:1
]
3] When is lactic acid formed in our muscles?
[Marks:2
]
4] What is Plaster of Paris? How it is obtained from Gypsum. Write chemical reaction. Give its one
use.
[Marks:2
]
5] A solution of potassium chloride when mixed with silver nitrate solution, an insoluble white
substance is formed. Write the chemical reaction involved and also mention the type of the
chemical reaction?
[Marks:2
]
6] Two green plants are kept separately in oxygen free containers, one in the dark and the other in [Marks:2
continuous light. Which one will live longer? Give reasons.
]
7] Three 2 resistors, A, B and C, are connected as shown in Figure. Each of them dissipates
energy and can withstand a maximum power of 18 W without melting. Find the maximum
current that flow through the three resistors.
[Marks:3
]
8] Give the events that occur during photosynthesis.
[Marks:3
]
9] Describe the steps involved in reflex action.
[Marks:3
]
10 Write chemical equations for the reactions taking place when
]
(i) zinc sulphide is heated in air
(ii) calcination of zinc carbonate is done
[Marks:3
]
(iii) when manganese dioxide is heated with aluminium powder
11 (a) Why do we store silver chloride in dark coloured bottles?
]
(b) How does slaked lime is prepared from calcium oxide.
12 Write the balanced chemical equations for the following reactions:
]
(a)
Sodium carbonate on reaction with hydrochloric acid in equal molar concentrations
gives sodium chloride and sodium hydrogen carbonate.
[Marks:3
]
[Marks:3
]
(b)
Sodium hydrogen carbonate on reaction with hydrochloric acid gives sodium chloride
and liberates carbon dioxide.
13 A student prepared solutions of (i) an acid and (ii) a base in two separate beakers. She forgot to [Marks:3
] label the solutions and litmus paper is not available in the laboratory. Since both the solutions
]
6
9
are colourless, how will she distinguish between the two?
14 What happens at the synapse between two neurons?
]
15 (a)
]
?
[Marks:3
]
How much current will an electric bulb draw a 220V source if the bulb filament is 1200
(b)
How much current will an electric heater draw from a 220V source if the resistance of
the heater is 100 ?
16 Name various plant hormones. Give one function of each.
]
[Marks:3
]
[Marks:3
]
17 What does the direction of thumb indicate in the right-hand thumb rule? In what way this rule is [Marks:3
] different from Fleming's left hand rule?
]
18 What is biomass? Explain the principle and working of a biogas plant using a labeled schematic
] diagram.
[Marks:3
]
19 (a) Why does a current carrying conductor kept in a magnetic field experience force? On what
] factors does the direction of this force depend? Name and state the rule used for determination
of direction of this force.
(b) A magnetic compass shows a deflection when placed near a current carrying wire.
How will the deflection of the compass get affected if the current in the wire is increased?
Support your answer with a reason.
[Marks:5
]
OR
(a) What is the function of an earth wire? Why is it necessary to earth metallic appliances?
(b) Two circular coils A and B are placed closed to each other. If the current in the coil A is
changed, will some current be induced in the coil B? Give reason.
20 (a) Salt A commonly used in bakery products on heating gets converted into another salt B
] which itself is used for removal of hardness of water a gas C is evolved. The gas C when passed
through lime water turns it milky. Identify A, B and C.
(b) Write any two uses of bleaching powder
OR
(a) Write word equations and then balanced equations for the reaction taking place when –
(i) dilutesulphuric acid reacts with zinc granules.
(ii) dilute hydrochloric acid reacts with magnesium ribbon.
(b) What is a neutralisation reaction?
(c) Give two important uses of washing soda.
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0
[Marks:5
]
21 (a)
]
Write the electron dot structures for sodium magnesium and oxygen.
(b)
Show the formation of Na2O and MgO by transfer of electrons.
(c)
What are the ions present in these compounds.
(d)
Why do ionic compounds have high melting point.
OR
Give reason:
(a) Platinum, gold and silver are used to make jewellery.
[Marks:5
]
(b) Aluminium is a highly reactive metal, yet it is used to make utensils for cooking.
(c) Reaction of nitric acid with metals generally does not evolve hydrogen gas.
(d) Carbonate and sulphide ores are usually converted into oxides during the process of
extraction.
(e) Copper is used to make hot water tanks and not steel (an alloy of iron).
22 Find out the following in the electric circuit given in Figure.
]
(a)
Effective resistance of two 8 resistors in the combination.
(b)
Current flowing through 4
resistors.
(c)
Potential difference across 4
(d)
Power dissipated in 4 resistor.
(e)
Difference in ammeter readings, if any.
resistance.
[Marks:5
]
OR
A current of 1 ampere flows in a series circuit containing an electric lamp and a conductor of 5
when connected to a 10 v battery. Calculate the resistance of the electric lamp. Now if a
resistance of 10 is connected in parallel with this series combination, what change (if any) in
current flowing through 5 conductor and potential difference across the lamp will take place?
Give reason. Draw circuit diagram.
23 Draw the diagram of alimentary canal of man and label the following parts:
]
· Mouth
· Oesophagus
7
1
[Marks:5
]
· Stomach
· Intestine
Where do carbohydrates, proteins and fats get digested in human beings?
OR
What is the advantage of having four chambered heart? Support your answer with a diagram of
the section of a human heart.
24 To study the dependence of current (I) on the potential difference (V) across a resistor R, two
] students used the two set ups shown in figure A and B respectively. They kept the contact point J
in four different marked, (a), (b), (c), (d) in the two figures
[Marks:1
]
For the two students the ammeter and voltmeter reading will be maximum when the contact J is
in the position:
A.
(d)
in both the set ups
B.
(a)
in both the set ups
C.
(a)
in set up A and (d) in set up B
D.
(d)
in set up A and (a) in set up B
25] The pH values of distilled water, fruit juice and sodium bicarbonate were measured using pH
papers. What is the correct decreasing order of pH values
A.
Water > Fruit juice > Sodium bicarbonate
B.
Fruit juice > Water > Sodium bicarbonate
C.
Water > Sodium bicarbonate > Fruit juice
D.
Sodium bicarbonate > Water > Fruit juice
[Marks:1]
26] In an experiment to test the pH, of a given sample using pH paper, four students recorded the
following observations.
Sample taken.
(I) Water
pH paper colour turned to.
Green
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2
[Marks:1]
(II) Dil. HCl
Red
(III) Dil. NaOH
Blue
(IV) Dil. Acetic acid
Orange
Which one will have pH value of 7?
A.
II
B.
III
C.
IV
D.
I
27] A student performed the starch test on a leaf. Some steps involved are shown below.
[Marks:1]
The correct sequence of steps should be:
A.
D,
C,
B,
A
B.
A,
B,
C,
D
C.
B,
C,
D,
A
D.
A,
C,
D,
B
28] Four students studied reactions of zinc and sodium carbonate with dilute hydrochloric acid and
dilute sodium hydroxide solutions and presented their results as follows. The '√' represents
evolution of gas whereas 'X' represents absence of any reaction,
[Marks:1]
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3
The right set of observations is that of student
A.
B
B.
C
C.
D
D.
A
29] A sample of soil is mixed with water and allowed to settle. The clear supernatant solution turns
the pH paper yellowish-orange. Which of the following would change the colour of this pH paper [Marks:1]
to greenish-blue?
A.
Lemon juice
B.
Vinegar
C.
Common salt
D.
An antacid
30] Which one is not observed when aluminium is added to solution of copper sulphate?
A.
The solution is blue in the beginning
B.
The final solution becomes colourless
C.
A brown mass is deposited on the surface
of Aluminium
D.
The final solution becomes light green
31] A more reactive metal displaces a less reactive metal from the aqueous solution of the latter.
From the following sets tell which one represents a correct picture of both the possible (√)
reactions and impossible (x) reactions between metals and the solutions of different salts.
A.
B.
C.
D.
Metal
Al2(SO4)3
CuSO4
FeSO4
(b) Cu
√
x
X
Metal
Al2(SO4)3
CuSO4
FeSO4
(c) Fe
√
√
X
Metal
Al2(SO4)3
CuSO4
FeSO4
ZnSO4
(d) Zn
x
√
X
√
Metal
Al2(SO4)3
CuSO4
FeSO4
(a) Al
x
√
√
32] In the experiment on finding the equivalent resistance of two resistors connected in parallel
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[Marks:1]
[Marks:1]
[Marks:1]
three students connected the Voltmeter in their circuits in the three ways X, Y and Z shown here.
The voltmeter has been correctly connected in.
A.
cases X and Y only
B.
cases Y and Z only
C.
cases Z and X only
D.
all the three cases
33] Identify the circuit (Figure) in which the electrical components have been properly connected.
[Marks:1]
A.
(i)
B.
(iii)
C.
(iv)
D.
(ii)
34] The rest positions of the needles in a milliammeter and voltmeter when not being used in a
circuit are as shown in the figure. The zero error and 'least count' of these two instruments are.
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[Marks:1]
A.
(+4mA, -0.2V) and (1mA, 0.1V)
respectively
B.
(+4mA, -0.2V) and (2mA, 0.2V)
respectively
C.
(-4mA, +0.2V) and (2mA, 0.2V)
respectively
D.
(-4mA, +0.2V) and (2mA, 0.1V)
respectively
35] Two students (A) and (B) connect their two given resistors R1 and R2 in the manners shown
below.
Student A connects the terminals marked b1 and c1 while student B connects the terminals
marked d2 and c2 in their respective circuits at the points marked X and Y.
Which one of the following is correct in relation to above arrangement
A.
both the students will determine the
equivalent resistance of the series
combination of the two resistors
B.
both the students will determine the
equivalent resistance of the parallel
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[Marks:1]
combination of the two resistors.
C.
Student A will determine the equivalent
resistance of the parallel combination
while student B will determine the
equivalent resistance of the series
combination of the two resistors.
D.
Student A will determine the equivalent
resistance of series combination while
student B will determine the equivalent
resistance of parallel combination of the
two resistors
36] A well stained leaf peel preparation when focused under high power of the microscope would,
show
A.
epidermal cells, stomata, guard cell with
many nuclei and one chloroplast cell
B.
stomata, and guard cells without nuclei or
chloroplasts
C.
Stomata, but no guard cells or epidermal
cells
D.
epidermal cells, stomata, guard cells each
with one nucleus and many chloroplasts
[Marks:1]
37] A student draws the following sketch of stomatal apparatus the part I, II, III and IV are labeled
differently by four students.
[Marks:1]
The correct labeling out of the following is
A.
B.
I
Guard cell
stoma
II
III
starchgranule
nucleus
IV
I
Guard cell
starch granule
II
III
Nucleus
stoma
IV
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C.
D.
I
cytoplasm
chloroplast
II
III
stoma
nucleus
IV
I
Cytoplasm
nucleus
II
III
stoma
chloroplast
IV
38] Given below are four different set ups to show that CO2 is released during respiration.
[Marks:1]
A.
A
B.
B
C.
D
D.
C
39] What is the use of KOH solution in this experiment?
[Marks:1]
A.
Absorbs O2 released by germinating
seeds
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B.
Absorbs moisture released by the seeds
C.
None of these
D.
Absorbs CO2 released by germinating
seeds
40] To observe cells in an onion peel, we must prepare the slide by mounting on it:
A.
Crushed pulp of onion
B.
Dry scale leaf
C.
Green leaf of onion
D.
Thin layer of fleshy leaf of onion
[Marks:1]
41] B1, B2 and B3 are three identical bulbs connected as shown in the Figure. When all the three
bulbs glow, a current of 3A is recorded by the ammeter A.
(i) What happens to the glow of the other two bulbs when the bulb B1 gets fused?
[Marks:1]
A.
B2 gets dimmer and B3 glows brighter
B.
B3 gets dimmer and B2glows brighter
C.
B3 and B2 both will glow more
D.
The glow of the bulbs B2 and B3 will
remain the same
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9
Chapter 8: HOW DO ORGANISMS REPRODUCE?
GIST OF THE LESSON
Reproduction :It is the process by which organisms produce new organisms of its own kind.
Importance of reproduction :i) It involves transmission of genetic material from generation to generation ,&
ensures the survival of the species. ii) It introduces variations & accumulation of variations over a period leads
to evolution.
Basic event in the process of reproduction:-Creation of a DNA copy
Sexual Reproduction in flowering plants
1)
Parts of flowers
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 Pollination: self and cross pollination
 Gametogenesis: Two male gametes and one female gamete is formed
 Double Fertilization: One of the male gamete fuses with egg cell. This fusion is called syngamy
and another male gamete fuses with diploid polar nuclei. This fusion is called triple fusion.
 Syngamyresultsin to zygote and triple fusion results in to primary endosperm cell.
Sexual Reproduction in Human
1)
Puberty: The age, when reproductive organs become functional, (in female 10-12 years, in male 13-14 years).
2)
Male reproductive system in human beings.
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3)
Female reproductive system in human beings.
Reproductive system of human female
4)
Reproductive system of Human male
Reproductive healtha) To have awareness about STDs, (sexually transmitted disease).
b) Some common STDs are gonorrhea, syphilis & HIV-AIDS.
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2
MIND MAP
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3
FORMATIVE ASSESSMENT-III
Very short answer type question:
Note: each question carries 1 mark.
1)
What is reproduction?
2)
Have you seen seeds of rose or potato? Name some plants whose seeds you may have seen.
3)
Can an amoeba and hydra reproduce like human beings?
4)
What changes are observed in the uterus if fertilization occurs?
5)
Define fertilization?
Short answer type questions
Note: each question carries two marks:
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4
1)
In the human body, what is the role of (a) seminal vesicles (b) prostate gland?
2)
State the difference between menarche and menopause?
3)
What is variation? Mention the importance of DNA copying in reproduction.
HIGHER ORDER THINKING SKILLS (HOTS) QUESTIONS
1)
Give two reasons for the appearance or variation among the progeny formed by sexual reproduction.
2)
Colonies of yeast fail to multiply in water but multiply in sugar solution. Give one reason.
3)
Malaria parasite divides into many daughter individual simultaneously through multiple fission. State an
advantage the parasite gets because of this type of reproduction.
4)
What is the importance of DNA copying in reproduction?
5)
How does reproduction help in providing stability to population of species?
6)
Why is vegetative propagation practised for growing some types of plants?
7)
Why would be the reason for adopting contraceptive methods ?
8) Name those parts of flower , which serve the same function as the following do in the animals a) testies
b) Eggs, c) Ovary ,d) Sperms.
IMPORTANT QUESTIONS
Q.1) Why is variation beneficial to the species but not necessary for the individual?
Q.2) What is the advantage of reproduction through spores in the case of Rhizopus?
Q.3) The simple animals such as planaria can be cut into number of pieces and each
piece grows into a complex organism. What is this process known as?
Q.4) Name the unicellular organism which caused the disease known as kala-azar.
Q.5) Which process taking place in the nucleus of a cell leads to variation in the
offspring during reproduction?
Q.6) What causes joining up of stock and scion in grafting technique of vegetative
propagation in plants? Define the terms stock and scion. Name one positive trait each
of the plant contributing scion and stock should have.
Q.7) Which type of layering is done in Jasmine?
Q.8) Where does fertilization takes place in human female?
Q.9) Why is it said that “sexual reproduction promotes diversity of characters in the
offsprings”?
Q.10) What happens if the fallopian tubes are partially blocked and the ovulated eggs
are prevented from reaching the uterus?
Q.11) Name the causative organism of syphilis and gonorrhoea.
Q.12) Why are variation possible in progeny of sexually reproductive individuals?
ANSWERS
Ans-1) Variation is beneficial to the species as it enables a species for its survival. A
favourable variation makes an organism to live better in a changed environment and
anunfavourable variation will not. So it is not necessarily true that a variation is
beneficial to the individual always.
Ans-2) The spores are covered by thick walls that protect them until they come into
contact with aother moist surface and can begin to grow.
Ans-3) Regeneration
Ans-4) Leishmania
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5
Ans-5) DNA copying
Ans-6) The stock and scion unite due to cambial cavity. Stock is the portion on which
grafting is done and it provides the roots. Scion is the portion of the plant which is
grafted on the other plant and it contributes the stem. The plant contributing scion
should have large sized fruits and the plant contributing stock should have deep root
system.
Ans-7) Air Layering (Gootee)
Ans-8) Oviduct (fallopian tube)
Ans-9) It is because sexual reproduction results from the fusion of two gametes
coming from two different and sexually distinct individuals. This leads to variation, is
necessary for evolution.
Ans-10) Fertilization may take place but the zygote may develop in the tube instead of
uterus.
Ans-11) Treponemapallidum and Nisseriagonorrhoeae.
Ans-12) Variations are possible in progeny of sexually reproductive individuals
because copy of DNA in newly formed cell is not identical to copy DNA of original
cell.
QUESTION BANK FOR PRACTICE
Q1) Name those parts of the flower which serve the same function as the following do in the
animals
(1) Testes (2) Ovary (3) Eggs (4) Sperms
Q2) ‘Malarial parasite’ divides into many daughter individuals simultaneously by multiple
fission state an advantage the parasite gets because of this type of reproduction.
Q3) Is copy of DNA formed identical to original cell? If yes or no, how is it beneficial to a
species?
Q4) An individual may have a good health even when the whole of reproductive system is
removed. What is the function of the reproduction system then?
Q5) Grafting is a common method of obtaining a superior plant from two different plants.
Explain.
Q6) The buds produced in the notches along the leaf margins of Bryophyllum plant fall on
the soil and develop into new plants. Which type of reproduction is this?
Q7) What is the name of the yellow powdery substance present in the anther of a flower.
Q8) What substances are contained in oral pills used as contraceptives.
Q9) Which life process ensures that a plant or animal species will not disappear from the
earth?
Q10) Fertilization is possible if ovulation has taken place during middle of the menstrual
cycle. Give reasons.
Q11) Why is the female reproductive system more complex than the male reproduction
system?
Q12) A potato is cut into a number of small pieces, these potato pieces are placed on wet
cotton kept in a tray. After a few days, green shoots and roots appear only from some potato
pieces and not from all potato pieces why?
Q13) What is the significance of human testis being located in the scrotum?
Q14) How the surgery methods are misused by people to prevent pregnancy?
Q15) Why is the number of sperms produced always more than the number of eggs
produced?
Q16) DNA copies generated will be similar but may not be identical to the original. Explain.
Q17) After fertilization, name the part in each case which develops into
(a) the fruit (b) the seeds.
Q18) What is meant by implantation in human reproductive system.
Q19) Justify why the male reproductive system is called “urinogenital system”.
Q20) Justify that parthenogensis is not the same as asexual reproduction.
Q21) State the advantages of tissue culture in growing plants.
Q22) What is meant by internal fertilization and external fertilization? Explain with
examples.
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6
Q23) Mention any two functions of human ovary.
Q24) What is the significance of syngamy and triple fusion?
Q25) (a) Draw the diagram showing the germination of pollen on the stigma. Label style,
male germ cell, ovule and female germ cell.
(b) What happens to the following parts of a flower after fertilization:
(i) Ovule
(ii) Zygote
(iii) Ovary
Q26) Name the following structures:
a. Primary sex organs in man and women.
b. Reproductive parts of a flower.
c. A barrier method of birth control used by human.
(Q27) What is proliferative phase during menstrual cycle?
Chapter 9 : HEREDITY AND EVOLUTION
GIST & KEY OF THE LESSON
IMPORTANT CONCEPTS / TERMS
GENETICS: The study of heredity and variation.
HEREDITY : The transmission of characters (or traits) from the parents to their offspring.
VARIATION: The differences in the characters among the individuals of a species.
CHROMOSOME: A thread like structure in the nucleus of cell formed of DNA which Carries the genes.
GENE: A unit of DNA or a segment of DNA which controls or specific characteristic of an organism.
ALLELES: They are various forms of a gene which occur at the same particular position or locus over the
chromosomes.
DOMINANT GENE: The gene which decides the appearance of an organism even in the presence of an
alternative gene. RECESSIVE GENE: The gene which can decide the appearance of an organism only in
the presence of another identical gene.
GENOTYPE: It is the description of genes present in an organism.
PHENOTYPE: The characteristic which is visible in an organism.
F1 GENERATION: First filial generation – when two parents cross to produce progeny (offsprings) , then
their progeny is called F1 generation.
HYBRID: A new form of plant resulting from a cross of different varieties of or plant.
AUTOSOMES: The chromosomes except those involved in the determination of sex.
SEX-CHROMOSOME: The chromosomes determine the sex of an individual.
FOSSILS: The remnants or impressions of organisms that lived in the remote past.
EVOLUTION: The sequence of gradual changes which takes place in the primitive Organisms over
millions of years and new species are produced
PHYLOGENY: Evolutionary history of organism.
ONTOGENY: Developmental history of organism.
HOMOLOGOUS ORGANS: Organs which have the same basic structure and developmental origin but have
different function and appearance. E.g. fore limb of a frog , a bird and a man.
ANALOGOUS ORGAN: Organs which have different basic structures and developmental origin but perform similar
function. E.g. the wings of an insect and a bird.
VESTIGEAL ORGAN: Organs which are functionless and rudimentary now but was functional in the ancestor. E.g.
vermiform appendix, nictitating membrane.
BIOGENETIC LAW: It states that ―Ontogeny recapitualates phylogeny.‖
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7
Genetic Drift: Random change in the frequency of genes in a population over successive generations.
MIND MAP
FORMATIVE ASSESSMENT –III
TICK THE CORRECT OPTION:
1. The number of chromosomes in human ovum is
a.21
b.22
c.23 d.24
2. An example of homologous organs is
a. Our arm and a dog’s foreleg b./our seethe and an elephant’s tusk
c. potato and runners of glans. D. all of these.
3. The hereditary units are:
a. Segments of RNA b. Genes. c. Chromosomes f. Chromatin
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8
4. The science dealing with biotechnology is called.
a.Heredity and variation
b. paleontology
c. genetics
HOTS
1.If a trait exists in 10% of a population of an asexually reproducing species and a trait B in 60% of
the same population which trait is likely to have arisen earlier?
2.Which of the following is not the example of artificial selection ?
A)Colours of rose b.Flavours of mangoes 3.colours of beetle 4.Starch quality of wheat.
3. Explain how advantages variations like long neck help an organism like Giraffe to survive
better?
4. Which of the following is the clearly acquiered trait in human beings?
a.Intelligence
b.Height
C.Swimming
d. Skin colour.
5. Why are human beings, who look different from each other size and colour belongs to the same species?
6. Acquiered characters are not inherited .Give reasons.
7. All the human races like Africans, Asians ,European and others might have from common ancestors
provide few evidence in support of the view.
8. How is genetic drift different from natural selection? From the diagram given below which case
shows natural selection?
Refer to diagram 9.7 ,page 147 of textbook.
IMPORTANT QUESTIONS
1. How one is change adopted to perform different functions? Give one example
2. What happened when Mendel crossed two traits of a character in a pea plants?
3. Who provided experimental evidence to support theory of origin of life from
inanimate matter?
4. Why are asexually reproducing organisms capable of showing hereditary
features?
5. If the sperm bearing Y-chromosome fertilizes the egg, the child born will not
be entirely like his father. Why is it so?
6. A normal pea plant bearing colored flowers suddenly start producing white
flowers. What could be the possible cause?
7. Mention any two recessive traits of garden pea.
8. Write the characteristics on the basis of which duck-biled platypus is
considered as a link between reptiles and mammals.
9. Why are the small number of surviving tigers a cause of worry from the point
of view of genetics?
10. What is called phylogenetic system of classification?
11. Is it true that when a new species is emerged, the old species is eliminated and
why?
12. What will be the percentage of ab gametes produced by AaBb parent?
13. Mendel crossed a pure white recessive pea plant with a dominant pure red
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flowered plant. What will be the first generation of hybrids?
14. In evolutionary terms, which among-bacteria, spider, fish and chimpanzee
have a “better” body design? Why or why not?
15. What is an offspring?
16. Why are traits acquired during life-time of an individual not inherited?
17. Name the chemicals which were essential for origin of life.
18. Why males are called heterogametic?
19. What is the percentage possibility a couple of having daughters?
20. Name 2 organisms in which sex determination is regulated by environmental
factors.
21. What are inherited traits? Give one example.
22. When Mendel crossed a Tall plant with a dwarf plant, no medium height
plants were obtained in F1 generation. Why?
23. The gene type of green stemmed tomato plants is denoted as GG and that of
purple stemmed tomato plants as GG when these two are crossed.
i. What colour of stem would you expect in F1 progeny?
ii. Give the percentage of purple stemmed plants if F1 are self pollinated.
iii. In what ratio would you find the gene types CG and Gg in the F2
progeny?
24. The human hand, cat paw and horse foot when studied in detail show the same
structure of bones and point towards a common origin.
i. What do you conclude from this?
ii. What is the term given to such structures?
25. What are the causes of variations in clones?
26. How do we know how old a fossil is?
28. Only variation that confer and advantage to an individual organism will
survive in a population. Do you agree with this statement? Why or why not?
ANSWERS
1. In evolution, one change occurred initially is used to perform other functions.
For example, feathers were evolved for warmth, later they were adapted for
flight.
2. Only dominant trait appeared in F1
3. Miller and Urey
4. Asexual reproduction tends to preserve the similarities among all the
individuals belonging to a give line of descent. Therefore, asexually
reproducing organisms are capable of showing hereditary features.
5. It is so because the other sex chromosome, ie the X-chromosome will also
have its effects and other autosomes of the egg will also show their
characteristics.
6. The appearance of white flowers is due to mutation.
7. Dwarf (height of plant), wrinkled seed
8. The characteristic resembling reptiles is laying of eggs and the characteristics
resembling mammals is presence of mammary glands.
9. As the population of tigers is decreasing, there is loss of genes from the gene
pool and there can’t be recombinations and variations, thus no evolution.
10. Classification based on evolutionary relationships of organisms.
11. No,it is not true that when a new species is emerged, the old species is
eliminated. Because when there is a change in any species, the change is only
in a part or a few members of the species population. If the newly generated
species after genetic change is better in any way, it will get more opportunity
to survive and if the genetic change is against the environment, it will die.
Thus, unchanged members of other species may also remain and tend to live in
changed environment.
12. 25 percent
13. All red
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14. Chimpanzee have the better body design as compared to others given. They
are better adapted for locomotion, communication and thinking.
15. In sexual reproduction organisms raised are as a result of crossing over and
exchange of gene segments and are known as offspring.
16. Traits acquired during life-time of an individual not inherited because change
in non-reproductive tissue or somatic cells cannot be passed on to the DNA of
germ cells. Thus, the acquired trait will die with the death of the individual. It
is therefore non-heritable and cannot be passed on to its progeny.
17. Proteins and nucleic acid
18. Because they have dissimilar sex chromosomes.
19. 50 percent
20. Turtle, lizard
21. The characteristics which are transmitted from parents to their offsprings are
called inherited traits. E.g. free and attached earlobes.
22. Because dominant genes express themselves and suppress the effect of
recessive genes. So no medium sized plants were obtained.
23.
i. Colour of F1 progeny – Green
ii. Percentage of purple stemmed plants in F2 generation ¼ or 25%.
iii. Ratio of genotypes GG and Gg 1:2
24. They have a common ancestry (i)Homologous organs
25. i. inaccuracies during DNA copying
ii. Effect of environment termed acquired variation.
iii. Mutations are sudden stable changes which are discontinuous
inheritable as produced due to changes in genetic make-up.
26. There are two methods:
i. Relative method when we dig into the earth, the fossils we find closer
to the surface are more recent than the fossils we find in deeper layers.
ii. By detecting the ratios of different isotopes of the same element in the
fossil material.
28. We agree with the statement.
All the variation do not have an equal chance of surviving in the environment
in which they find themselves. The chances of surviving depend on the nature
of variation. Different individuals have different kind of advantages. A
bacteria that can withstand heat will survive better in heat wave.
FORMATIVE ASSESSMENT –IV
QUIZ
A. Decomposers are also called __________
B. Producers prepare their _____________
C. Ozone layer is destroyed by ___________
D. Ecology is the study of the interaction of_________ with each other and their surroundings.
Activity; To study vestigial organs in Human beings. Students define vestigial organs and discuss
the use of every part of the body. Then come to the conclusion.
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Chapter-10,Light : Reflection and Refraction Gist of chapter
1.Light is a form of energy. It brings the sensation of sight. It is a form of electromagnetic
radiation.
2. The first theory of light was forward by Newton which treats light as a particle called
corpuscle.
3. light propagates as a wave and is emitted and absorbed as a particle. Light have dual
nature.
4. Maxwell proved that light has wave nature; it is an electromagnetic transverse wave and
does not require medium to propagate.
5. Light wave travels with a speed of 3x108m/s in space.Itisa universal constant. Its speed
depends on the medium.
6. Light gets reflected when it falls on polished surface like mirror.
When light falls on a smooth surface, it returns into same medium, this is known as
reflection of light.
The following are the laws of reflection.
1) The angle of incidence ( I ) = angle of Reflection ( r )
2) The incident ray, the normal to the mirror at the point of incidence and the
reflected ray lies in the same plane.
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7. The reflecting surface of a spherical mirror may be curved inwards or outwards. A
spherical mirror , whose reflecting surface is inwards, that is faces towards the centre of the
sphere, is called a concave mirror, A spherical mirror whose reflecting surface is curved
outwards is called a convex mirror.
a) Centre of curvature : The centre of the sphere of which the mirror is a part is
called the radius of curvature. It is denoted by C.
b) Radius of curvature : The radius of the sphere of which the mirror is a part is
called the radius of curvature. It is denoted by R.
c) Focal length : The distance between the pole and the focus is called the focal
length. It is denoted by F . The focal length is half the radius of curvature (R).
F = R/2
d) Real Image : When the rays of light , after reflection from a mirror, actually
meet at a point, then the image formed by these rays is said to be real. Real
images can be obtained on a screen.
e) Virtual image : When the rays of light , after reflection from a mirror, appear to
meet at a point, then the image formed by these rays is said to be Virtual.
Virtual images can’t be obtained on a screen.
8. Image formation by a concave mirror for different positions of the object –
POSITION OF
THE OBJECT
AT INFINITY
BEYOND C
POSITION OF
THE IMAGE
SIZE OF THE
IMAGE
NATURE OF THE
IMAGE
AT THE
FOCUS F
HIGHLY
REAL AND
DIMINISHED,PIONT INVERTED
SIZED
BETWEEN F
AND C
DIMINISHED
REAL AND
INVERTED
AT C
AT C
SAME SIZE
REAL AND
INVERTED
BETWEEN F
AND C
BEYOND C
ENLARGED
REAL AND
INVERTED
HIGHLY ENLARGED
REAL AND
INVERTED
ENLARGED
VIRTUAL AND
ERECT
AT THE FOCUS
AT INFINITY
F
BETWEEN
P(POLE) AND F
BEHIND THE
MIRROR
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9. Image formation by a convex mirror for different positions of the object –
POSITION OF THE
OBJECT
AT INFINITY
Between infinity and
the pole P of the
mirror
POSITION OF THE
IMAGE
SIZE OF THE
IMAGE
NATURE OF THE
IMAGE
AT THE FOCUS
F, behind the mirror
HIGHLY
VIRTUAL AND
DIMINISHED,PIONT ERECT
SIZED
BETWEEN P
AND F, Behind the
mirror
DIMINISHED
VIRTUAL AND
ERECT
10. Uses of the concave mirror :1. It is used in torches, searched lights and vehicles heads lights to get powerful beams
of the light.
2. They are used as saving mirrors to see a larger image of the face.
3. The dentists used concave mirror.
4. They are used as reflectors in cinema projectors.
5. In solar cookers to focus the sun light.
11. Uses of the convex mirror :1. As rear view mirror because it produces erect and diminished images. Since the image
is small in size, so the field view is increased.
2. It is used as a reflector for street lighting purposes.
a) The image is unmagnified, virtual and erect in a plane mirror.
b) Focal length of a plane mirror is infinity.
c) Power of a plane mirror is zero.
12. Magnification :- Magnification produced by a spherical mirror gives the relative extent
to which the image of the object is magnified with respect to the object size. It is expressed
as the ratio of the height of the image to the height of the object. It is usually represented by
‘m’
m = height of the image (h’)/ height of the object (h)
It also be related to the object distance (u) and image distance (v), then
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m=
ℎ′
ℎ
=
𝑣
𝑢
The height of the object is taken to be positive as the object is
usually placed above the principal axis. The height of the image should be taken as positive
for virtual image. However it is to be taken as ( -)ive for real image. A ( -)ive in the
magnification that the image is real and ( +)ive for virtual image.
13. Light shows bending when it travels from one medium to another the phenomena is
called refraction of light.
Reflection of the light :The change in the direction of propagation of light when it goes from one medium to
another medium is called refraction of light.
1) When a ray of light goes for a rarer medium to a denser medium, it bends towards the
normal .
2) When a ray of light goes for a denser medium to a rarer medium, it bends away
fromthe normal .
There is a change in the wavelength of light when it moves from one medium to
another .similarly frequency and speed of light will also
change.
14. Laws of refraction :1. The incident ray, the normal to the mirror at the point of incidence and the
refracted ray lies in the same plane.
2. The ratio of sine of the angle of incidence to the sine of angle of refraction is a
constant for a given pair of medium.
µ=
sin 𝑖
sin 𝑟
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whereµ is a constant, called refractive index.
15. Refraction through glass slab :incident ray
normal
incidentray
i normal
r
air medium
refracted ray
glass medium
µ=
normal
sin 𝑖
sin 𝑟
16. It should be noted that, if the spherical lenses are surrounded by a material with a
refractive index greater than that of the lens, the convex lens gets converted into a concave
lens or vice-versa.
17. Power of a lens is equal to the reciprocal of its focal length (f) , where focal length is
measured in meter.
P = 1/f
Its SI unit is Dioptre (D).
The power of a convex lens is + and for concave - .
FORMULAE
1. Relation between radius of curvature and focal length f = R/2
2. Mirror formula: 1/f= 1/v +1/u = 2 /R
3. M = h2 /h1 = -v/u
4. n = c/v
5.1n2 = 1/2n1
6.1n2 = n2/n1= sin i/sin r
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7.a n w = x/y
8. Lens formula 1/v –1/u = 1/f
9. Magnification of a lens m =I/O = h2 /h1 = v/u
10. P= 1/f metre
11. P = p1 + p2 + p3 + …….
12. n21=sin i/sin r=n2/n1=v2/v1=λ1/λ2
…………………………………………………………………………………………………
…………………………
Short answer type question( 1 & 2 marks)
Q1.Why does it takes sometimes to see in a dim room when you enter the room from bright
sunlight outside?
ANS: In the bright iris causes the pupil to become smaller so that only a small portion of
light enter the eye and rods of the retina are also adjusted in the same way. but when a
person enter in to dim light each iris takes sometimes to increase the diameter of the pupil so
that more amount of light can enter the eyes to see the objects clearly and rods of the retina
also takes some time to adjust –themselves to get the picture of the object in the dim light.
Q2. Can we see a rainbow on the moon?
ANS:No, since there is no atmosphere on the moon.
Q3.Does a beam of light give a spectrum on passing through a hollow prism?
ANS:No,this is because dispersion of light cannot occur through a hollow prism containing
air.
Q4. Where is the image formed in a convex mirror, when the object is anywhere infront of it
?
Ans .Between pole and focus, behind the convex mirror.
Q5. A person uses concave mirror for shaving, where should he position his face infront of
it ?
Ans. Between pole and principal focus.
Q6. A ray of light is incident on a concave mirror along its principal axis. What willbe the
angle of reflection?
Ans. Angle of reflection = 0
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Q7. What will happen to ray of light when it travels from rarer medium to a densermedium ?
Ans. Bends towards the normal.
Q8. What does negative sign in the value of magnification of a mirror indicate?
Ans. Image is real.
Q9. Name the point inside the lens through which a ray of light goes undeviated?
Ans. Optical centre.
Q10. Which of the two has a great power? A lens of short focal length or a lens of
large focal length?
Ans. Lens of short focal length.
Q11. Name the lens which always gives an erect and diminished image?
Ans. Concave lens.
Q12. Which mirror is used as rear view mirror in vehicles and why ?
Ans. Convex mirror, wider field of view.
Q13. Define one dioptre?
Ans. One dioptre is the power of a lens of focal length one meter.
Q14. The size of an object is 2cm.The magnification produced by a mirror is +1. Whatis the
size of the image?
Ans. +2cm, because m=I/O , +1=I/2 =+2
Q15. When a ray of light passes from a denser medium to a rarer medium which angleis
greater: angle of incidence or angle of refraction?
Ans. Angle of refractions.
Q16. An image formed in a spherical mirror has magnification -2.Is the image real
orvirtual?
Ans. Real.
Q17. The power of a lens is -2D. Is the lens convex or concave?
Ans. Concave lens.
Q18. Focal length of a convex mirror is 10cm.Find the radius of curvature of the
mirror?
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Ans. 20cm.
Q19. An object is placed at a distance of 50cm from a convex mirror. State
twocharacteristics of the image formed.
Ans. (1) Image is virtual and erect.
(2) Image is diminished.
Q20.Write two uses of concave mirror.
Ans. (1) Used as reflectors for automobile headlights
(2) Used as shaving mirror.
Q 21. An object 1cm high produces a real image 1.5 cm high, when placed at a distanceof
15 cm from concave mirror. Calculate the position of the image.
Ans. – v/u = h’/h , -v/-15 = -1.5/1
v = 15x 1.5 = -22.5cm.
Q22. Find the power of a concave lens of focal length 2m.
Ans. – p = 1/f=1/-2 = -0.5D.
Q23. Which phenomenon occurs when light falls on(a) highly polished surface (b)
atransparent medium ?
Ans. (a) Reflection of light.
(b) Refraction of light.
Q24. What will happen to a ray of light when it falls normally on a surface ?
Ans. No bending of light ray occurs. It means light rays goes straight from one medium to
another.
Q25. What is absolute refractive index ?
Ans.When first medium is taken as vaccum, the refractive index of second medium iscalled
as absolute refractive index.
Q26. The magnification “ m “ for a mirror is +1 what does this signify ?
Ans. (a) Image is of same size as the object.
(b) Image is virtual and erect .
Long answer questions 5 marks
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Q1. State the laws of reflection. Draw a ray diagram for incidents ray, normal and
reflected ray.
Ans Laws of reflection:
1) The incidence ray, the reflected ray and the normal at the point of incidence, all lie in the
same plane.
2) The angle of reflection and the angle of incidence are equal.
Ref : above
Q2. Define ray and beam of light, explain the refraction of light and draw a ray
diagram for refraction of light through glass slab.
Ans: Ray and beam: the straight line indicating the path of the light (arrow- direction is
called a ray. A
bundle of rays originating from the same source of light in a particular direction is called a
beam of
light.
Diagram as above
Q3.What is an image? Draw ray diagram when a object is in between infinity and
centre of curvature of the convex mirror.
Ans: Image: the point of convergence or the point form where the light appears to diverge
after reflection or refraction is called image.
Draw the ray diagram
Q4.What is angle of incidence and angle of reflection? Find the angle of incidence and
angle of reflection, if the angle between the incidence ray and mirror is 500 .
Ans Angle of incidence is the angle between the incident ray and the normal at the point of
incidence is
called angle of incidence. Angle of reflection: the angle between the reflected ray and the
normal at the point of reflection is called angle of reflection.
a) 400
b) 400
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Q5.What are the rules for drawing ray diagram for the reflection of light for concave
and convex mirror?
Ans In order to draw ray diagram, following rules are used:
1) The rays of light passing parallel to the principle axis will coverage at the focus after
reflection.
2) The rays of light passing through the focus will emerge parallel to the principle axis after
reflection.
3) The rays of light passing through the center of curvature will all retrace their both after
reflection.(as it is normal at the point of incidence)
4) The rays of light falling at the pole get reflected at the same angle on the other side of
principle
axis.(Laws of reflection)
Q6 Write mirror and lens formulae.
Ans Mirror formula: 1/f= 1/v +1/u where f, v and u are the focal length, image distance and
object
distance.
Lens formula: if u, v and f are the object distance, image distance and focal length
respectively
then 1/f=1/v-1/u
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Chapter 11,
Human eye and colorful world
Key Concepts
1. The human eye is like a camera. Its lens system forms an image on a light sensitive screen
called the retina.
2. The eye ball is approx. spherical in shape with a diameter of 2.3cm.
3. The human eye has the following parts:-
(a) Cornea:-The transparent spherical membrane covering the front of the eye.
(b) Iris:-The colored diaphragm between the cornea and lens.
(c) Pupil:-The small hole in the iris.
(d) Eye lens:-It is a transparent lens made of jelly like material.
(e) Ciliary muscles:-These muscles hold the lens in position.
(f) Retina:-The back surface of the eye.
(g) Blind spot:-The point at which the optic nerve leaves the eye. An image formed at this
point is not sent to the
brain.
(h) Aqueous humour:-A clear liquid region between the cornea and the lens.
(i) Vitreous humour:-The space between eye lens and retina is is filled with another liquid
called Vitreous humour.
Figure in NCERT book
4. In the eye, the image is formed on the retina by successive refraction at the cornea, the
aqueous humuor, the lens and the vitreous humuor. Electrical signals then travel along the
optic nerve to the brain to be interpreted. In good light, the yellow spot is most sensitive to
detail and the image automatically formed there.
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5. Accommodation:-The ability of the eye to focus both near and distant objects, by
adjusting the focal length, is called the accommodation of the eye or the ability of the ciliary
muscles to change the focal length of the eye lens is called accommodation.
6. Defects of the eye:- Although the eye is one of the most remarkable organs in the body, it
may have several abnormalities, which can often be corrected with eye glasses, contact
lenses, or surgery. The various defects from which an eye can suffer are (i)
Hypermetropia or long sightedness. (ii) Myopia or short sightedness and (iii)
Astigmatism. (iv) Presbyopia.
7. Hypermetropia, hyperopia or long sightedness:-A person suffering from this defect
can see distant objects clearly but cannot see nearby objects clearly. In this defect,
the near point lies further away from 25cm.Hypermetropia (far sightedness- the image
of nearby objects is focused beyond the retina) is corrected by using a convex lens of
suitable power. The eye losses its power of accommodation at old age.
8. Hypermetropia is due to the following reasons:-(i) Either the hyperopic eye ball is too
short or
(ii) The ciliary muscle is unable to change the shape of the lens enough to properly focus the
image that is the focal length of the eye lens increases.
9. Myopia or short sightedness or near sightedness:-A person suffering from myopia or short
sightedness can see nearby objects clearly but cannot see the faraway objects clearly.
Myopia (shortsightedness -the image of distant objects is focused before the retina) is
corrected by using a concave lens of suitable power.
10. Presbyopia is the defect of human eye due to which an old p erson cannot read and write
comfortably. That is why presbyopia is also called old sight.
11. As our two eyes are separated by a few centimeters, each eye observes a slightly
different image. Our brain combines the two views into one and we get to know how close
or far away the things seen are.
12. The smallest distance, at which the eye can see objects clearly without strain, is called
the near point of the eye or the least distance distinct vision. For a young adult with normal
vision, it is about 25cm.
13. The distance between far point and near point of the eye is called range of vision of the
eye.
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14. Spectrum is a band of distinct colours we obtain when white light is split by
theprism.
15. Causes of dispersion:-Every colour has its own characteristic wave length or
frequency. Different colours move with same speed in air/vacuum. But their speeds
in refracting media like glass are different. Therefore, refractive index of the medium
for different colours is different. As a result, different colours un dergo different deviations
on passing through the prism. Hence, differentcolours emerge from the prism along
different directions.
16.In any medium other than air/vacuum red light travels the fastest and violet light travels
the slowest.
17. When we pass white light through two identical prisms held side by side with their
refracting edges in opposite direction; the first prism disperses white light into seven
colours and the second prism recombines the seven colours into white light. Thus light
emerging from second prism is white.
18. A rainbow is formed due to dispersion of light by tiny droplets of water which act as
prisms.
19. Scattering of light causes the blue colour of the sky and the reddening of the sun at
sunrise and sunset.
1) Red light is used for danger signal
2) Cause of Color blindness.
3) Sky appears black in Moon.
4) Rainbow is seen on a rainy day in the presence of sunlight.
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5) A person with a myopia eye cannot see objects beyond a distance of 1.5m. What
would be the
power of corrective lens? Which type of lens is used?
6) What do you understand by myopia? Write two causes of it?
7) What do you mean by far point and near point of eye?
8) What is presbyopia? State the cause of it and how is it corrected?
9) Explain:
1) why does sky look blue on a clear day
2) Twinkling of stars.
10) What is hypermetropia? State two causes of hypermetropia with help of ray diagrams
show:
1) The eye defect hyperopia.
HOTS
1.Why does it takes sometimes to see in a dim room when you enter the room from
bright sunlight outside?
ANS: In the bright iris causes the pupil to become smaller so that only a small portion of
light enter the eye and rods of the retina are also adjusted in the same way. but when a
person enter in to dim light each iris takes sometimes to increase the diameter of the
pupil so that more amount of light can enter the eyes to see the objects clearly and rods
of the retina also takes some time to adjust –themselves to get the picture of the object in
the dim light.
2Can we see a rainbow on the moon?
ANS:No, since there is no atmosphere on the moon.
3.Does a beam of light give a spectum on passing through a hollow prism?
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ANS:No,this is because dispersion of light cannot occur through a hollow prism
containing air.
1. Name the place where image is formed in the eye?
2. Name the muscular diaphragm that controls the size of the pupil.
3. What is the cause of dispersion of light?
4. Give the cause of cataract of eye.
5. Which color has got more wavelength?
6. What makes bees respond to ultraviolet light.
7.
What is the nature of image at retina?
8. Name the point inside the lens through which a ray of light goes deviated?
9. Name the photographic film equivalent to our eye .
10.Why does a glass slab not disperse white light?
11.Why do we not perceive the depth of a lake ?
12.Name two causes of Myopia, Hypermetropia and presbiopia.
13.Name the liquids that keep our eye soft.
14.What causes rainbow formation?
15.What is Mirage?
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chapter 12 Electricity
Gist of chapter
The rate of flow of electric charges [electrons] is called electric current.
electric current I = Q/t
The SI unit of electric charge is coulomb (C), which is equivalent to the charge contained in
nearly 6 × 1018 electrons and Charge on 1 electron = – 1.6 × 10–19 C.
When one coulomb of charge flows through a conductor for 1 second then current flowing
through it is called One ampere. The SI unit of electric current is ampere.
OR
Coulomb: It is the S.I. unit of charge. One coulomb is defined as that amount of charge
which repels an equal and similar charge with a force of 9 x 10 9 N when placed in vacuum
at a distance of 1 meter from it.
Static and current electricity: Static electricity deals with the electric charges at rest while
the current electricity deals with the electric charges in motion.
Electric circuit: The closed path along which electric current flows is called an ‘electric
circuit’.
Conventional current: Conventionally, the direction of motion of positive charges is taken
as the direction of current. The direction of conventional current is opposite to that of the
negatively charged electrons.
Electric field: It is the region around a charged body within which its influence can be
experienced.
Ohm’s law of electricity- The potential difference, V, across the ends of a given metallic
wire in an electric circuit is directly proportional to the current flowing through it, provided
the Temperature remains the same.
Electric circuit diagram of ohm’s law
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V∝I
V/I = constant (R)
V = IR
Where R is a constant for the given metallic wire at a given temperature and is
called its resistance.
Resistance –: The property of a conductor to resist the flow of charges through it is called
resistance.
R = V/I , its SI unit is Ohm
Resistance of a conductor is directly proportional to length of wire. Resistance of a
conductor is inversely proportional to cross-sectional area of wire.
R = ρ L/A
Where ρ (rho) is constant of proportionality called resistivity.
The equivalent resistance of the combination of resistance in a series is equal to the sum of
their individual resistances.
R = R1 + R2 + R3
A set of resistance connected in parallel has equivalent resistance R given by
1/R=1/R1+1/R2+1/R3
Electrostatic potential: Electrostatic potential at any point in an electric field is defined as
the amount of work done in bringing a unit positive charge from infinity to that point. Its
unit is volt
1. Positive charges move from higher to lower potential regions. Electrons, being
negatively charged, move from lower to higher potential regions.
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2. Potential difference between two points: The Potential difference between two
points in an electric field is the amount of work done in bringing a unit positive
charge from one to another.
Potential difference = Work done/Charge or V = W/Q
3. One volt potential difference: The Potential difference between two points in an
electric field is said to one volt if one joule of work has to be done in bringing a
positive charge of one coulomb from one point to another.
4. Electric potential difference (V) = W/q = 1Joule /1 coulomb= J/C = volt
5. Galvanometer: It is device to detect current in an electric circuit.
6. Ammeter: It is device to measure current in a circuit. It is always connected in series
in a circuit.
Voltmeter: It is a device to measure potential difference. It is always connected in
parallel to the component across which the potential difference is to be measured.
8. Electric energy: It is the total work done in maintaining an electric current in an
electric circuit for given time.
Electric energy, W = VIt = I2Rt joule
7.
9. Electrical power: Electrical power is the rate at which electric energy is consumed
by an appliance.
P = W/t = VI = I2R = V2/R
Watt: It is the S.I. unit of power. The power of an appliance is 1 watt if one ampere of
current flows through it on applying a potential differences of 1 volt across its ends.
1 watt = 1 joule/1 second =1 volt x 1 ampere
or 1 W = 1 Js-1 = 1 VA
Kilowatt hour: It is the commercial unit of electrical energy. One kilowatt hour is the
electric energy consumed by an appliance of 1000 watts when used for one hour.
1 kilowatt hour (kWh) = 3.6 x 106 J
Short answer type question
Q1. What is an electric current?
Answer: Electric current is the amount of charge flowing through a particular area in unit
time
Q2. What is the source of electric charge?
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Answer: the cells or a battery
Q.3 The torch gives light only when its switch is on. What does a switch do?
Answer: A switch makes a conducting link between the cell and the bulb.
Q4. Will current flow more easily through a thick wire or a thin wire of the same material,
when connected to the same source? Why?
Answer: Current will flow more easily through a thick wire as there is less resistance
because resistance of a conductor is inversely proportional to cross-sectional area of wire.
Q.5 On what two factors the current through a conductor depends upon?
Answer: The current through a conductor depends upon its resistance and the potential
difference across its ends.
Q6.Define power and derive expression for it?
Answer: The rate, at which electric energy is dissipated or consumed, is termed as electric
power. The power P is given by,
P = w/t = VQ/t = VI
Q.7 Why is the fuse used in electric circuits?
Answer: It protects circuits and appliances by stopping the flow of any unduly high electric
current. If a current larger than the specified value flows through the circuit, the temperature
of the fuse wire increases. This melts the fuse wire and breaks the circuit.
Q8. Define 1Volt? OR, What is meant by saying that the potential difference between two
points is 1 V?
Answer: When 1 joule of work is done to move a charge of 1 coulomb from one point to the
other it is said to be 1V potential difference.
Q9. What is a circuit diagram?
Answer: A schematic diagram of electric circuit in which different components of the circuit
are represented by the symbols is called a circuit diagram.
Q10. What is the reciprocal of resistivity called?
Answer: Reciprocal of resistance is conductance So the reciprocal of resistivity is called
Conductivity.
Hots
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Q.1 Why are fairy decorative lights always connected in parallel?
Answer: When the fairy lights are connected in series the resistance offered will be greater
and brightness of the bulbs will be affected. But in parallel connection all the bulbs will
glow with same intensity and if any more bulbs gets fused the other bulbs will continue to
glow.
Q. 2 Calculate the number of electrons constituting one coulomb of charge.
Answer charge (Q) = no. of electrons (n) x charge on one electron (e)
1 coulomb = n x (1.66 x 10-19)
n = 1/1.66 x 10-19 = 6.25×1018 =6 x1018
Q. 3 What do you mean by Electric potential and potential difference?
Answer: The work done to move a unit charge from infinity to a given point is called
Electric potential or potential at a point. Hence, potential can be measured in term of the
work done in moving charge against the force of repulsion. It is a scalar quantity.
Electric potential difference between two points in an electric circuit is the work done to
move a unit charge from one point to the other.
If W work done in bringing unit charge q from one point to the other.
Then Electric potential difference (V) = W/q = 1Joule /1 coulomb= J/C
The SI unit of electric potential difference is volt (V) .
Q. The potential difference between the terminals of an electric heater is 60 V when it draws
a current of 4 A from the source. What current will the heater draw if the potential
difference is increased to 120 V?
Resistance between the terminals of an electric heater R = V/ I = 60/4 = 15 Ω
Amount of current flow through heater if the potential difference is increased to 120 V = I =
V/R = 120/15 = 8A
Hence, the current through the heater becomes two times i.e. 8 A.
……………………………………………………………………………………….
Q. Define resistivity of material.
Q. What is the power of torch bulb rated at 2.5V and 500mA?
Q.
Why series arrangement not used for connecting domestic electrical
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appliances in a circuit?
Q. Which has higher resistance – a 50W bulb or a 2.5W bulb and how many
times?
Q. What is the direction of flow of conventional current?
Q. Why is it not advisable to handle electrical appliances with wet hands?
Q. Two electric bulbs marked 100W 220V and 200W 200V have tungsten
filament of same length. Which of the two bulbs will have thicker filament?
Q. How does the resistance of a wire vary with its area of cross section?
Q. Draw the following symbols
i) Battery
ii) Switch closed
iii) Resistor of resistance R
iv) Voltmeter
Q. A geyser is rated 1500W, 250V. This geyser is connected to 250V mains.
Calculate –
i) The current drawn
ii) The energy consumed in 50hrs.
iii) The cost of energy consumed at Rs. 2.20 per kWh.
Q. What is the function of an electric fuse? Name the material used for
making fuse. In household circuit where is fuse connected?
Q. Write one important advantage of using alternative current. How
alternating current differ from direct current?
Q. What is the difference between short circuiting and overloading?
a) Draw diagram showing three resistors R1, R2 and R3 in series.
b) Two resistors of resistance 4 and 12
i)
In parallel
ii)
In series
Calculate the values of effective resistance in each case.
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Chapter 13 -Magnetic effect of current
Gist of chapter
The magnetism is the property possessed by certain bodies of attracting or repelling other
bodies of magnetic substances.
 Magnet: (i) is an object that attracts objects made of iron, cobalt & nickel.
(ii) Comes to rest in North-South direction, when suspended freely.
 Magnets are used: (i) In radio & stereo speakers, (ii) In refrigerator doors, (iii) on
audio & video cassettes players, (iv) On hard discs & floppies of computers & (v) in
children’s toys.
 Magnetic field: The area around a magnet where a magnetic force is experienced is
called a magnetic field. It is a quantity that has both direction & magnitude.
 Magnetic field lines: Magnetic field is represented by field lines. They are lines
drawn in a Magnetic field along which a North magnetic pole moves. Magnetic field
lines are called as Magnetic lines of force.
 Properties of Magnetic field lines:
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They do not intersect each other. It is taken by convention that magnetic field lines emerge
from North pole and merge at the South pole. Inside the magnet, their direction is from
South pole to North pole. Therefore magnetic field lines are closed curves.

Magnetic field lines due to a current through a straight conductor (wire)- consist of
series of concentric circles whose direction is given by the Right hand thumb rule.
Maxwell's Right Hand Grip Rule : The direction of the magnetic field around a current carrying conductor can be
explained by a simple rule known as Maxwell's right hand grip rule. If we hold
the current carrying wire in our right hand in such a way that the
thumb is stretched along the direction of the current, then the curled fingers give the direc
tion of the magnetic field produced by the current.
 Fleming’s Left hand rule: Stretch the thumb, forefinger and middle finger of left hand
such that they are mutually perpendicular. Forefinger points in the direction of
magnetic field and centre finger in the direction of current, then the thumb gives the
direction of force acting on it.
 The strength of the magnetic field at the centre of the loop(coil)depends on:
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(i)
The radius of the coil- The strength of the magnetic field is
inversely proportional to the radius of the coil. If the radius
increases, the magnetic strength at the centre decreases.
(ii) The number of turns in the coil: As the number of turns in the
coil increase, the magnetic strength at the centre increases,
because the current in each circular turn is having the same
direction, thus the field due to each turn adds up.
(iii) The strength of the current flowing in the coil: as the strength
of the current increases, the strength of thee magnetic fields also
increases.
2. Electromagnet: An electromagnet consists of a long coil of insulated copper wire
wrapped on a soft iron core.
(Refer to figure 13.11, page no. 229 of N.C.E.R.T Text book)
3. Electric motor: A device that converts electric energy to mechanical energy.
4. Principle of Electric motor: When a rectangular coil is placed in a magnetic field
and a current is passed through it, force acts on the coil, which rotates it
continuously. With the rotation of the coil, the shaft attached to it also rotates.
5. Electromagnetic induction: Electricity production as a result of magnetism
(induced current) is called Electromagnetic induction.
6. Fleming’s Right hand rule: gives the direction of induced current.
Stretch the thumb, forefinger and middle finger of right hand such that they are
mutually
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perpendicular. Forefinger points in the direction of magnetic field and centre finger in
the
direction of induced current, then the thumb gives the direction of motion of the
conductor.
7. Electric generator: A devise that converts mechanical energy to electric energy.
(Refer to figure 13.19, page no. 236 of N.C.E.R.T Text book)
Electric generator is of two types- (i) A.C generator (ii) D. C generator
8. Principle of Electric generator: Electromagnetic induction.
9. Domestic electric circuits: (Refer to figure 13.20, page 238 of N.C.E.R.T Text
book)
10.We receive electric supply through mains supported through the poles or cables.
In our houses we receive AC electric power of 220V with a frequency of 50Hz.
The 3 wires are as follows- (i) Live wire- (Red insulated, Positive)
(ii) Neutral wire- (Black insulated, Negative)
(iii) Earth wire- (Green insulated) for safety measure to
ensure
that any leakage of current to a metallic body does not give
any serious shock to a user.
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11.Short circuit: is caused by touching of live wires and neutral wire
12.Fuse: is a protective device used for protecting the circuits from short circuiting
and over loading.
Questions :1. On what effect of an electric current does an electromagnet work?
A. Magnetic effect of electric current
2.
A.
3.
A.
What is the frequency of AC (Alternating Current) in India?
50Hz
On what effect of an electric current does a fuse work?
Heating effect of electric current
Other important questions :-
1.
State two uses of electromagnet.
2.
An electron moving along X – axis in a magnetic field along Y – axis. In
which direction will the electron deflected.
3.
State Fleming’s left hand rule.
4.
What is the importance of earth wire?
5.
Should a copper wire be used as a fuse wire? If not, why?
6.
Give two points of difference between and electromagnet and permanent
magnet.
7.
Draw the lines of force indicating field direction of the magnetic field
through and around
i)
ii)
Single loop of wire carrying electric current.
A solenoid carrying electric current.
8.
What id magnetic field? How is the direction of magnetic field at a point
determined?
9.
Give four features of domestic electric wiring.
10.
Draw a schematic diagram of domestic wiring system and write its main
features.
11.
Match the following:
A
B
i) Right hand thumb rule
a) Force on a conductor in a
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magnetic field
b) Direction of magnetic field of
straight conductor
c) Direction of induced current in
conductor
d) Polarity of any end of a solenoid.
ii) Fleming’s left hand rule
iii) Fleming’s right hand rule
12.
a) Draw a labelled diagram to show how electro – magnet is made.
b) What is the purpose of soft iron core in making electromagnet?
13.
Write two differences between AC and DC current and draw diagram also.
14.
1.
a)
b)
c)
d)
What is magnetic line of force?
Can two magnetic lines of force intersect? Give reason.
Magnetic lines of force are endless. Comment.
How do the field lines of the regions of strong field different
from those of weak field?
2.
a) What is a solenoid?
b) Is the magnetic field of a solenoid similar to that of a bar
magnet?
c) State the two factors by which the strength of magnetic field
inside a solenoid can be increased.
d) How will you determine the direction of the magnetic field due
to a current – carrying solenoid?
3.
a) What is an electromagnet?
b) What is the effect of placing an iron core in a solenoid?
c) What type of core should be used inside a solenoid to make an
electromagnet?
d) Give two advantages of electromagnets.
15.Name the sources of direct current.
16.Why don’t two magnetic lines intersect each other?
17.What is the role of split ring in an electric motor?
18.What is an earth wire?
19. What type of core should be used inside a solenoid to make an
electromagnet?
20.
Name the SI unit of magnetic field.
21.
What is the principle of an electric motor?
22.
A generator converts energy from one form to another. What is this energy
conversion?
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23.
Which wire (live, neutral or earth) goes through the switch?
24.
Are different appliances connected in series or parallel in a house?
25.
What is the colour convention for live, neutral and earth wires?
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Chapter 14-SOURCES OF ENERGY
KEY CONCEPTS & GIST OF THE LESSON
Characteristics of a good fuel:
(i)
(ii)
(iii)
(iv)
(v)
(vi)
High calorific value
Less smoke
Less residue after burning
Easy availability
Inexpensive
Easy to store and transport
Fossil fuels: were formed millions of years ago, when plants and animal remains got
buried under the earth and were subjected to high temperature and pressure conditions.
E.g.: Coal, Petroleum, etc.
These fossil fuels are non renewable sources of energy and cause environmental
problems due to pollution.
Thermal power plants:
(i)
Use coal, petroleum and natural gas to produce thermal electricity.
(ii) Electricity transmission is very efficient.
(iii) The steam produced by burning the fossil fuels runs the turbine to produce
electricity
Hydro power plant:
(i)
It is the most conventional renewable energy source obtained from water falling
from a great height.
(ii) It is clean &non polluting source of energy.
(iii) Dams are constructed to collect water flowing in high altitude rivers. The
stored water has a lot of potential energy.
(iv) When water is allowed to fall from a height, potential energy changes to kinetic
energy, which rotates the turbines to produce electricity.
Disadvantages of Hydro power plant:
(i)
Highly expensive to construct.
(ii) Dams cannot be constructed on all river sites.
(iii) Large areas o human habitation and agricultural fields get submerged.
(iv) People face social and environmental problems.
Non conventional sources:
(1) Bio mass:
 It is the source of the conventionally used fuels that are used in our
country. E.g.: Cow dung cakes, fire-wood, coal, charcoal
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 Bio gas: It is a mixture of gases produced during decomposition of bio
mass in the absence of Oxygen. (Anaerobic Respiration). Methane is the
major component of bio gas.
 Bio gas plants: Animal dung, sewage, crop residues, vegetable wastes,
poultry droppings, etc. are used to produce Bio gas in Bio gas plants.
(1) Wind energy:
 It can be converted into mechanical and electrical energy.
 Kinetic energy of the wind is used in running of wind mills, which are
used to lift water, grind grains, etc.
 Wind mill-(Refer to figure 14.5, page no. 247 of N.C.E.R.T Text book)
Advantages: (i) Eco friendly (ii) Renewable
Disadvantages: (i) Wind speed not uniform always.
 (ii) Needs a large area to erect series of wind mills.
 Big amount of investment is needed.
 Out put is less as compared to investment
(2) Solar energy:
o Solar radiations can be converted electricity through solar cells
(photovoltaic cells).
o Photovoltaic cells convert solar radiations directly into electricity
through silicon solar cells.
o Solar cells arrange on a large flat sheets form a solar panel.
o Solar cookers are painted black from outside and a large glass plate
to trap solar radiations by green house effect.
o (Refer to figure 14.6, page no. 249 of N.C.E.R.T Text book)
o Advantages of Solar cookers:
(i) Eco friendly
(ii) Renewable
(iii) Used in rural areas.
(iv) Retains all the nutrients in food due to slow cooking.
o Disadvantages of solar cooker:
(i) Silicon cells are expensive.
(ii) Solar radiations are not uniform over earth’s surface.
(iii) Cannot be used at night or on cloudy days.
(iv) Cannot be used to make chapattis for frying as these
require a temperature of 1400C or more.
(Maximum temperature of 1000C only can be
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achieved in a solar cooker)
o Other solar devices- Solar water heater, Solar furnace
(3) Geo thermal energy:
(i)
Energy harnessed from the heat of the sun is called Geo thermal energy.
(ii) Magma is formed when this heat melts the rocks. The molten rocks and
hot gases are called magma
(iii) The magma gets collected at some depths below the earth’s surfaces.
These places are called ‘Hot spots”
(iv) When underground water comes in contact these hot spots, it changes
into steam, which can be used to generate electricity.
o Advantages of Geo thermal energy:
(i)
Renewable
(ii)
Inexpensive
o Disadvantages of Geo thermal energy:
(i)
Only few sites available for harnessing energy.
(ii) Expensive
(4) Nuclear energy:
(i) Energy released when some changes take place in the nucleus of the
atom of a
substance, is called Nuclear energy.
(ii) It is used for heat generation, fuel for marine vessels.
o Advantages of Nuclear energy:
(i)
Alternative source of energy due to depletion of fossil fuels.
(ii) From a small amount of fuel, a large amount of energy is
released.
o Disadvantages of Nuclear energy:
(i)
Risk of nuclear waste leakage
(ii) High cost of setting up of nuclear plant
(iii) Pollution of environment.
(5) Energy from the sea(A) Tidal energy: Locations in India – Gulf of Kutch, Gujrat & W. Bengal
(i) Depends upon harnessing the rise and fall of sea level due to tidal action.
(ii) Dams are constructed across a narrow part of sea and turbine converts
tidal
energy into electrical energy.
Disadvantages: Uniform tidal action is not seen
(B) Wave energy:
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(i) Kinetic energy of the waves of sea are used to rotate turbines..
(ii) These turbines generate electrical energy
1.
QUESTIONS
2. Name the materials used for making solar cells.
A. Silicon, Germanium and Selenium
3. What fraction of solar energy reaches the earth’s surface?
A. 47%
4. Name the process that produces a large amount of energy in the sun.
A. Nuclear fusion
5. Why is biogas called a clean fuel?
A. Because it- (i) leaves no ash (ii) does not cause pollution (iii) does not
produce any poisonous gas.
Other important questions :-
1.Which component of solar radiations produces heat?
2.Name a form of energy that can be harnessed from the oceans.
3.Name the main component of biogas.
4.Name a fuel which is considered cleaner that CNG.
5.What is common between an atom bomb and a nuclear reactor?
6.What is the main transformation of energy during working of a windmill?
7.What are the conditions to achieve nuclear fusion?
8.
Name the component of sunlight, exposure to which may cause skin
cancer.
9.
Flowing water possess which type of energy.
10.
Name one place in India where wind energy power station is installed.
11.
What is a solar panel?
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12.
What type of energy transformation takes place during winding of
spring of a clock?
13.
Write two differences between renewable and non – renewable sources
of energy.
14.
What is the principle of solar cooker? Name two types of solar cooker.
15.
Name any two types of harmful nuclear radiations emitted during
nuclear fission.
16.
What is thermal power plant? Where it is preferably situated?
17.
What is the principle of solar cooker? Give two limitations and two
advantages of solar cooker.
18.
Name the fuel for hydro power plant. Mention two advantages and
disadvantages of producing electricity at the hydro power plant.
19.
Explain why:
a) It is difficult to burn a piece of wood fresh from a tree.
b) Pouring dry sand over the fire extinguishes it.
c) It is difficult to use hydrogen as source of energy.
20.
What are the different types of energies obtained from sea? Explain.
a) What is a principle of Biogas?
b) Explain it working in brief.
c) Draw a labelled diagram of biogas.
22. A) What is a good source of energy?
21.
B) Name one good source of energy.
C) It is a renewable source of energy?
23. A) Is it conventional or non – conventional source of energy?
24. What other name is give to it?
25. What is a fossil fuel?
26. Name any other two fossil fuels.
27. Which is the ultimate source of all forms of energy?
a) Can you explain?
b) Name some renewable source of energy arising due to sun.
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c) Name some non – renewable source of energy arising due to sun.
d) Why is the energy contained in fossil fuels considered due to sun’s energy?
e) Name any source of energy not influenced by sun’s energy.
28. What is the principle of nuclear energy?
B) What are the kinds of nuclear reaction?
c) Which of these can be used for destructive purposes?
d) Which of these can be used to produce energy for common use?
e) What is nuclear fission?
f) Name two substances which are easily fissionable.
g) What are these substances called?
h) What is this phenomenon of breaking up of radioactive isotopes called?
i) Name the rays emitted.
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Chapter 15: OUR ENVIRONMENT
GIST
ENVIRONMENT: It is the sum total of all external conditions and influences that affect the life and the
development of organisms i.e.,it includes all the biotic and abiotic factors.
Differences between biodegradable & non – biodegradable wastes
Biodegradable waste
Non-biodegradable waste
1. These substances can be broken down into
simple & harmless substances by the action of
decomposers.
1. These substances cannot be broken down into
simple & harmless substances by the action of
decomposers.
2. They do not cause pollution.
2. They cause pollution.
3. They do not persist in the environment.
3. They persist in the environment for a long time.
4. E.g; paper, cotton, vegetable & fruit peel, urine
& faecal matter.
4. E.g.; plastics, insecticides& pesticides,
Radioactive wastes.
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Functions of ecosystem:a) Flow of energy
b) Cycling of nutrients(bio-geo chemical cycles).
FOOD CHAIN: The process of eating & being eaten to transfer food energy.
Food chains in a grass land:Producers Herbivores Carnivores (grass) (deer) (lion)
Importance of food chain: 1.It helps in transfer of food energy from one organism to another.
2. It is a pathway for the flow of energy.
3. It helps in understanding the interdependence amongst different organisms.
Trophic levels are the various steps in the food chain .
Producers --- first trophic level, Herbivores --- second trophic levels, Carnivores --- third trophic level Top
carnivores --- fourth trophic level
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10% LAW OF ENERGY FLOW – The energy available at any trophic level in a food chain is
10% of the previous one.
BIOLOGICAL MAGNIFICATION– Progressive accumulation of nonbiodegradable waste at
various trophic levels of food chain.
Food web: Several interconnected food chains form a food web.
Differences between food chain & food web
Food chain
Food web
1. The process of eating & being eaten to transfer food
energy.
1. It is a system of interconnected food chains.
2. It forms a part of food web.
2. It contains many food chains.
3. It has limited populations.
3. It has several populations of different species.
HOW DO OUR ACTIVITIES AFFECT THE ENVIRONMENT? Two major problems:a) Depletion of ozone layer
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b) Disposal of waste
Depletion of ozone layer The ozone layer protects all the organisms from the harmful ultra
violet rays. Ozone depleting substances: CFCs, N2O, CH4 , CCl4
These chlorine containing compounds are used in: Aerosols, solvents, refrigerants and fire
extinguishers. Ozone hole developed over Antartica. Effects of ozone depletion on human
health- Due to depletion of ozone layerUV radiations reaches the earth and cause: i) skin
cancer ii) increased chances of cataract iii) suppression of immune system
HIGHER ORDER THINKIN SKIILS (HOTS) QUESTIONS
1. Write any two ways of energy flow through an ecosystem.
2. Differentiate between biodegradable and non biodegradable with respect to the effect of biological
processes on them and the way they affect our environment.
3. Why is pond self-sustaining unit while an aquarium may not be? Justify the answer.
4. Arrange grasshopper, frog, grass, eagle and snake in the form of food chain.
5. If 1000 KJ energy is available at producer level, how much energy will be available at first carnival
level?
6. Why do most food chains have 3-5 steps only?
7. Select the biodegradable items from the list given blowPolythene bags, old clothes, wilted flowers, pencil shavings, glass bangles, bronze statue, vegetable
peels.
8. What will be impact on ecosystem if bacteria and fungi are removed from the Environment?
9. Express your feelings on the picture given down below. What will happen if all?
10. Carnivores are eliminated from the environment? What measures will you take to save?
Tiger?
HOTS Questions and Answers
Q.1 Why some substances are degraded and others not?
Q2. What limits the number of trophic levels in a food chain.
Q3. What will happen if decomposers are not there in the environment?
Q4. What is the harm of clay cups?
Q5. What will happen if all the carnivores are removed from the earth?
Q6. What will happen to grasslands if all the grazers are removed from there?
Q7. The number of malarial patients in a village increase tremendously, when a
large number of frogs were exported from the village. What could be the cause for it?
Explain the help of food chain?
Q8. State one reason to justify the position of man at the apex of most food chains?
Q9. Which food chains are advantageous in terms of energy?
Q10. Construct a food chain composing the following Snake, Hawk, Rats, Plants.
Q11. Name the process that is a direct outcome of excessive burning of fossil fuels?
Q12. If all the wastes we generate is bio-degradable what impact may this have on
the environment?
Q13. Write the harmful effect of ozone depletion.
Q14. Why food chains consists of three or four steps only?
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Q15. Which of the following will have the maximum concentration of harmful
chemicals in its body?
Peacock, Frog, Grass, Snake, Grasshopper
Q16. Why energy of herbivores never come back to the autotrophs?
Q17. What are decomposers and what is the importance of them in the ecosystem?
Q18. Give the correct sequence of various trophic levels in a food chain.
Q19. What is biological magnification and give its causes?
Q20. Are plants actually producers of energy?
ANSWERS
Ans-1. Different components of food are changed to simpler substances by digestive
enzymes and these enzymes are very much specific in nature and action. Similarly,
substances are broken down by bacteria and saprophytes. They are also very specific
Producers
Primary
Consumer
Secondary
Consumers
Tertiary
Consumers
in action and break down of the particular substance. Therefore, some substances are
biodegradable and other are non-biodegradable.
Ans-2. There is a loss of energy as we go from one trophic level to the next, this
limits the number of trophic levels in a food chain.
Ans-3. If decomposers are not there in the environment, the breakdown of the
complex organic substances into simple substances will not take place and natural
replenishment of the soil will not take place. So, presence of decomposers is essential
for the replenishment of soil and biogeochemical cycle of elements or substances.
Ana-4. Clay cups cause depletion of top fertile soil as they are formed from the same.
Ans-5. If all the carnivores are removed from the earth, the population of herbivores
will increase. Large population of herbivores will overgraze. As a result, all plants
will disappear from the earth surface and ultimately the earth may become a desert.
The biosphere will get disturbed which will lead to end of life on earth.
Ans-6. If all the grazers are removed from grassland, grass will grow unchecked. It
may help the growth of some organisms harmful to the animals and the animals which
feed on the grazers will die of starvation. The biogeochemical cycle will stop and the
whole biosphere will get disturbed.
Ans-7. Phytoplankton Zooplankton Mosquito larva Frog
In the absence of frog, more mosquito larva survive, giving rise to large number of
mosquitoes which cause increase incidence of malaria.
Ans-8. The position of man is at the apex of most food chains as he is an intelligent
organism and can take any advantageous position by manipulation.
Ans-9. The two step chains in which man is close to producer are advantageous. For
example, Producer Man
Ans-10. Plants Rats Snake Hawks
Ans-11. Global warming is a direct outcome of excessive burning of fossil fuels.
Ans-12.Cleaner environment without any pollution, more nutrients will be released
into the nutrient pool, will help to maintain ecological balance.
Ans-13.1. Cause the skin cancer
2. Damage to eyes
3. Immune system
Ans-14Since so little energy is available for the next level of consumers and for this
reason food generally consists of three or four steps. The loss of energy at the each
step is so great that very little usable energy remains after four tropic levels.
Ans-15.Grass Grasshopper Frog Peacock
Peacock will have maximum conc.
Ans-16.Energy of herbivorous never comes back to autotrophs as flow of energy is
always unidirectional. So once it passes the trophic level it is no longer
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available to the previous level.
Ans-17.The micro-organisms which break down the complex organic substances into
simple inorganic substances e.g. bacteria, fungi. Decomposers decompose the
complex substances into simple ones so that plants can use it again
Ans-18.
Tertiary
Consumers
Secondary
Consumers
Primary
Consumers
Producers
Ans-19.The increased concentration of chemicals at any trophic level is called
biological magnification. It occurs due to the excessive use of pesticides which enter
our food chain.
Ans- 20. No, plants are not actually producers of energy, they can trap the energy of
sun and can convert solar energy into chemical energy in the form of carbohydrates
and other food materials so they are called transducers.
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Chapter 16: Management of natural resources
GIST
1) Natural resources: it is stock of the nature such as air, water, soil, minerals, coal, petroleum, forest and
wildlife that are useful to mankind in many ways.
2) Pollution: it is defined as the undesirable change in physical, chemical or biological characteristics of our
soil, air or water, which harmfully affect human lives or the lives of other species.
3) pH of water: pH stands for ‘potential of hydrogen’. The acidic and basic character of aqueous solutions
can be described in terms of hydrogen ion and hydroxyl ion concentration a pH below 7 indicates an acid
solution and above 7 indicates an alkaline solution.
4) Three R’s to save the Environment: We can reduce pressure on the environment by applying the maxim
to ‘Reduce, Recycle and Reuse’ in our lives.
5) Sustainable Development: It is the development which can be maintained for a long time without undue
damage to the environment.
6) Need to manage our Resources: Our natural resources are limited. With the rapid increase in human
population, due to improvement in health care, the demand for all resources is also increasing.
7) Biodiversity: It is the existence of a wide variety of species of plants, animals and microorganisms in a
natural habitats with in a particular environment or of genetic variation with a species.
8) Wildlife: It means all those naturally occurring animals, plants and their species which are not cultivated,
domesticated and tamed.
9) Water harvesting: It means capturing rainwater where it falls or capturing the run off in a local area and
taking measures to keep the water clean by not allowing polluting activities to take place.
10) Fossil Fuels: These fuels are obtained from the remains of plants and animals, which got buried beneath
the earth millions of years ago, changed into coal, petroleum and natural gas due to excessive heat and
high pressure inside the earth.
11) Coal: It contains chiefly carbon and its compounds mainly nitrogen, oxygen, sulphur and hydrogen. It
also contains inorganic matter.
12) Non-renewable Energy Sources: These are energy sources which cannot be replaced easily when they
get exhausted and are also called conventional sources of energy. E.g.: Fossil fuels.
13) Uses of Fossil Fuels:
Coal: Thermal power plants and steam engines
Petroleum: Petroleum products like petrol and diesel are used as means of transport.
14) Management of Fossil fuels: The natural gas is a good alternative to fossil fuels like coal and petroleum.
The use of alternative source of non- conventional source of energy such as solar energy, wind energy,
biomass energy etc. Should be promoted to save the reserves of fossil fuels .biogas can also be used for
various purposes.
MIND MAP
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IMPORTANT QUESTIONS
1. What does the high level of total coliform count in river Ganga indicates?
2. What are “biodiversity hot spots”? What is the measure of the biodiversity?
3. Which programme was started to replenish forests?
4. Why scarcity of water is there in our country inspite of nature’s monsoon
bounty?
5. What is the effect of continuous depletion of ground water along coastal
region?
6. Why is dependence of man on nature greater than that of any other organism?
7. In addition to low rainfall, what are the other reasons for non-availability of
water in arid and semi-arid zones of our country?
8. Why is mining a big source of pollution?
9. Write two points to be kept in mind while storing water in tanks.
10. Write any two alternatives to dams.
11. Why do you think there should be equitable distribution of resources?
12. Which canal has brought greenery to considerable areas of Rajasthan?
13. What were the two main problems as a result of Tawa Irrigation Project?
14. Write the advantages of giving the control of water management to the
residents of the area?
15. State benefits of water harvesting.
16. How did ChipkoAndolan ultimately benefit the local population? Give any
three benefits?
17. Quote three instances where human intervention saved the forests from
destruction.
18. Why are environmentalists insisting upon sustainable natural resource
management? Give any four reasons.
ANSWERS
1. It indicates that water is contaminated by disease causing micro-organisms.
2. Forests are “biodiversity hot spots”. One measure of the biodiversity of an
area is the number of species found here.
3. Silviculture
4. It has taken place due to the following reasons:
(a) Failure to sustain water availability underground which has resulted largely
from the loss of vegetation cover.
(b) Diversion for high water demanding crops.
(c) Pollution from industrial effluents and urban wastes.
5. The effect of continuous depletion of ground water along coastal region will
lead to movement of saline sea water into freshwater wells then spoiling their
quality.
6. Man’s dependence on the environment is greater than that of other organisms
because man:
(a) Develops curiosity for more comforts and security.
(b) Consumes large amount of material and energy.
(c) Develops a new kind of socio-economic environment which consists of
things developed by man through his tools and techniques.
7. (a) Flowing of rain water and lack of management to harvest it.
(b) Ground water is pumped out for high water demanding crops.
(c) Water becomes unsafe and unusable due to mixing of urban wastes and
effluents from the industries.
8. Mining causes pollution because large amount of slag is discarded for every
tonne of metal extracted.
9. Storage tank should not be located close to the source of contamination and
should be accessible for cleaning.
10. Adopting water harvesting techniques and reducing the scale of floods through
better catchment management.
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11. We think that there should be equitable distribution of resources because not
only a handful of rich and powerful people, but all the people may get benefit
from the development of these resources.
12. Indira Gandhi Canal.
13. Water logging and increasing salinity
14. Water harvesting techniques are highly locality specific and the benefits are
localised. Thus, giving people the control over their local water resources ensures
that mismanagement and overexploitation of these resources is reduced.
15. a. Provides self-sufficiency to water supply
b. Conserves valuable ground water
c. Reduces cost for pumping ground water
d. Reduces local flooding and drainage problems
16. a. The locals benefitted from forest produces
b. The wild life and nature were conserved
c. The quality of air and soil was preserved
17. a. Contribution of Bishnoi movement
b. Building national parks
c. Encouraging wildlife sanctuaries
28. a. Non-renewable resources are limited, we should use them judiciously
b. We should encourage the use of renewable resources
c. We should preserve the environment for future generation
d. The benefits of the controlled exploitation should go to local people
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SUMMATIVE ASSESSMENT – II
Time: 3 Hrs
Max. Marks: 90
General Instructions
i) The question paper comprises of two Sections ,A and B.You are to attempt both sections.
ii) All questions are compulsory.
iii)There is no overall choice. However internal choice has been provided in Five marks
category.
iv) All questions of Section–A and all questions of Section –B are to be attempted separately.
v) Question numbers 1 to 3 in Section-A are onemark questions.These are to be answered in
one word or in one sentence.
vi) Question numbers 4 to 7 in Section–A are two marks questions.These are to be answered
in about 30 words each.
vii)Question numbers 8 to 19 in Section-A are three marks questions. These are to be answered
in about 50words each.
viii)Question numbers 20 to 24 in Section-A are five marks questions.These are to be answered in
70words each.
ix) Question numbers 25 to 42 in Section-B are multiple choice questions based on practical
skills. Each question is a one mark question. You are to select one most appropriate
response out of the four provided to you.
SECTION –A
1. In a food chain consisting of grass,frog,bird and insects, where will be the concentration of the
harmful chemicals maximum?
2. A small candle2.5cm in size is placed at 27 cm in front of concave mirror of radius of curvature 36
cm. If the candle is moved close to the mirror how will the screen has to be moved?
3. Write the formula of the sulphate of the element with atomic number13.
4. What is the role of seminal vesicles and prostate gland in Human male reproductive system?
5. Fossil fuels arebeing increasingly used a ssource of energy. List reasons for replacing these by
alternative sources of energy.
6. What are Isomers? State two properties of carbon which lead to the huge number of carbon
compound.
7. Explain the three R’s to save the environment with examples.
8. (a) Which two criteria did Mendeleev use to classify the elements in his periodic table?
(b) State Mendeleev’s periodic law.
(c) Why is it not possible to give a fixed position to hydrogen in Mendeleev’s periodic table?
9. (a) Give the structural difference between saturated and unsaturated hydrocarbons and also give
one example of each.
(b) Write IUPAC name of the following compound
O
||
CH3–CH2–CH2–CH2– CH2–C –
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3
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(c) What happens when ethanol is heated with concentrated H2SO4 at 443 K? Give the chemical
reaction.
10. A) Properties of the element are given below:Where would you locate the following elements
in the periodic table.
a. An metal stored under kerosene oil.
b. An element with variable valency (more than one)stored underwater.
c. An element which is tetravalent in organic chemistry.
d. An element which is an inert gas with atomic number2.
B) Why does atomic size decreases from left to right in a period and increases down the group
11. Write the full form of DNA and briefly explain DNA copying and its significance.
12. Why are bacteria and fungi called decomposers? List any two advantages of decomposers to the
environment.
13. Draw a neat diagram of human female reproductive system and label the following parts:
A) The site of fertilization.
B) The part which is responsible for providing shelter to the growing embryo.
C) The part in which ovum formation takes place.
14. Define the following with one example for each:
A) Genetic Drift.B) Natural selection.C) Reproductive isolation.
15. A) Give the laws of Refraction of Light.
B) Two mediums A and B with refractive index 1.33 and 1.50 are given. In which case
i. Bending of light is more.
ii. Speed of light is more. Justify your answer.
16. A) Define Magnification.
B)Aconvex lens of focal length 20cm produces 3 times magnified real image of an object . Find
the position of the object
17. A) Write the differences between real and virtual image
B) Why convex mirror is used as rear view mirror
18.A student is not able to see clearly the questions written on the blackboard placed at a distance
of 5m from him.
A) Name the defect of vision he is suffering from
B) What are the causes for this defect.
C) With the help of labeled ray diagrams show the defect and how this can be corrected?
19.‘Variation is beneficial to the species but not necessarily for the individual.’Give three reasons to
support it.
20. A) Draw a diagram showing germination of pollen on stigma of a flower.
B) Label pollen grain ,male germ cells ,pollen tube and female germ cell in the above diagram.
C) Explain the process of fertilization in plants.
OR
A) What are the different methods of asexual mode of reproduction?
B) Explain two methods—Fragmentation and regeneration with proper diagram.
21. A)Explain Mendel’s experiment with peas on inheritance of traits considering two visible
Contrasting characters.
B) Define the term Evolution. “Evolution cannot be equated with progress”. Justify this
statement.
22. A) Complete the following reactions.
(i) CH3COOH +NaOH
1
3
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Ni
(ii) R –C=C-R+H2
I I
RR
sunlight
(iii) CH4+Cl2
B) Draw the structures of(i) ethanoic acid (ii)butanone
C) What are esters? Give one use of ester.
OR
A)What are soaps?Why do soaps not produce lather in hard water?
B)Explain the mechanism of cleansing action of soap.
C)Will a micelle be formed in other solvents like ethanol also? Justify your answer.
23. Image characteristics of mirror and lens are given below.
A) Complete the table
B) Draw the ray diagram for any one case
SlNo.
Device
Position of Object
Position of Image
Nature ofImage
1
Concavemirror
2
Convex mirror
3
Concavelens
Beyond C
Behind themirror
Foranyposition
4
Convex lens
Away from2f
24.Two friends were playing in the garden. Suddenly, Akshay noticed seven colours in the sky. He
said to Sudeep“ wow , what is this?”. Sudeep explained
A)What is the name of this natural phenomena?
B) Which device can be used to obtain such a phenomena? Draw thediagram.
C) If Akshay was facing the colours then where was the sun?
D) What is the moral value which is shown by Sudeep.
SECTION-B
25.On adding concentrated NaOH solution to a testtube containing phenolphthalein, the
colourchange observed by a student would be:
A. Pink to colourless
B. Pink to blue
C. colourless to pink
D. Red to blue
26.Four students observed the colour and odour of acetic acid and its reaction with sodium
hydrogen carbonate. They tabulated their observations as given below.
Student
A
B
C
D
Colourofacetic acid
Blue
Colourless
Lightgreen
Light brown
Odourofacetic acid
Fruity
Smellofvinegar
Odourless
Rotten egg
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Actionwithsodium
Hydrogencarbonate
Gas evolveswithout bubbles
Effervescence
Gas evolves without bubbles
Effervescence
The correct set of observation is that of student
a) A
b) B
c) C
d) D
27. Which of the following is an example of soft water?
(a) Rainwater.
(b) Riverwater. (c) Well water. (d) Hand pumpwater.
28. Permanent hardness of water is due to the presence of :
a)hydrogen carbonates of calcium and magnesium
b) chlorides and sulphates of calcium and magnesium
c) hydrogen carbonates and sulphates of calcium and magnesium
d) chlorides and carbonates of calcium and magnesium
29. Which of the following is added to precipitate out all the soap from the aqueous solution?
a) Calcium chloride b) Sodium hydroxide c)Sodium carbonate d) Sodiumchloride
30. In a saponification reaction,which of the following is obtained as a byproduct:
a) Sodium hydroxide b) Sodium stearate c) Glycerol d) Sodium carbonate.
31. The process represented in the diagram below is the
a) Formation of spores in Amoeba
b) Formation of bud taking place in Amoeba
c) Identical gametes being formed in Amoeba
d) Formation of daughter cells in Amoeba
32. Which one of the following sketches does not illustrate budding in yeast
a) I
b) II
c) III
d) IV
33. Homology and analogy are helpful in studying and interpreting.
a)functional relationship b) commercial use of structures
c) structural relationship d)evolutionary relationship.
34. Students were given bean seeds and were asked to observe the embryo. They carried out
the Following steps.
I. Separated the cotyledons from each other.
II. Soaked the seeds overnight.
III. Observed the embryo using magnifying glass.
IV.Peeled off the seed coat carefully.
What is the correct order of the steps?
a)II,I,IV,III b)II,IV,I,III c)I,II,IV,III d) I,III,II,IV
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35. Which part of the embryo develops into shoot?
a) Plumule b) Radicle c) Cotyledon d) seed leaves
36. Analogy refers to similarity in
a) morphology b) Origin
c) Function d) Size
37. Which of the following lenses would you prefer to use while readings mall letters in a book
a) Aconvex lens of focal length 50cm
b) A concave lens of focal length 50 cm
c) A convex lens of focal length 5cm
d) A concave lensof focal length 5cm
38.A student carries out the experiment of tracing the path of a ray of light through a rectangular
glass slabs for same radius of angle of incidence. The student reported the following
observation
30
30
I
II
a) Angle of emergence is equal to angle of incidence
b) Lateral shift is greater for glasss lab
c) Lateral shift in both cases are equal
The correct observation is
a) I and II b) I c) I and III
39.A student obtained the sharp image of a candle flame using a concave mirror of radius of
curvature 20cm and tabulated as follows.
SlNo
ObjectDistanceincm
Image distance incm
I
15
30
II
60
13
III
20
35
In the above observation
a. The image will been larged for the observation II
b. The observation III is wrong
c. Both I and II are correct
d. I is correctand II is wrong
40.Blue colour of the sky and twinkling of stars are due to
a) Reflection and Atmospheric refraction of sunlight.
b) Scattering and Atmospheric refraction of sunlight.
c) Dispersion and scattering of sunlight.
d) Atmospheric refraction and scattering of sunlight.
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41.Convex lens of focal length 10cm each is placed as in shown in the diagram. An object is
placed at a distance of 20cm. Image of the first lens will act as the object for the second
lens.
Then,
a) Then the final image will be formed at the principle focus of these
cond lens. b) Then the final image will be formed at infinity.
c) Then the final image will be formed at 2f.
d) Then the final image will be formed between f and 2f.
42. A student obtained a sharp image of the grills of a window on his screen using a concave
mirror.
His teacher remarked that for getting better results ,a well lit distant object(preferably
the sun)
Should be focused on the screen.What should be done for this
purpose?
A) Move the screens lightly away from the mirror
B) Move the mirror slightly towards the screen
C) Move the screen and the mirror away from the object
D)Move the screen and the mirror towards the object
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