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54200825-SPM-Focus-Practise-Science

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CHAPTER 1: Scientific investigation
1.Study the following section
Iron nails rust easily when left outside the house.
(a) What the problem that can be identified?
(b) Make one hypothesis for the situation given.
(c) Identify the following variables:
(i)
Variable that is constant
(ii)
Variable that is manipulated
(iii)
Variable that responds
2. Diagram 2 shows the arrangement of apparatus to studt the relationship between the
Length of the thread and the duration of the swing of the pendulum.
(a) What are the variables involved in this experiment?
(i)
Variable that is constant.
(ii)
Variable that is manipulated.
(iii)
Variable that responds.
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(b) What is the relationship between the length of the thread and the duration of the swing of the
pendulum.
(c) If the height of the pendulum from the surface of the table is increased, predict the time taken for the
pendulum to swing.
(d) State one precautionary step when conducting this experiment.
3. An experiment is conducted to study the relationship between the force (N) and the extension of a spring.
The results are shown in Diagram 3.
(a) State the variable:
(i)
That is manipulated
(ii)
That responds
(b) What is the relationship between the forces (N)and the extansion of the spring (cm)?
(c) Study Diagram 3 and fill the data in the table below.
Force/N
Extansion of the spring/cm
(d) Predict the extension of the spring if a force of 6 N is applied.
4. Diagram 4 shows a part of the steps in a scientific investigation.
Identifying a problem
Making a hypothesis
Identifying the
variables
x
2
Cotrolling
the variables
(a) How can problem be identify?
(b) What is variable
(c) State three variables in a scientific investigations
(d) What should be done if the hypothesis made is not accepted by the experiment?
(e) Identify step x in the scientific investigation.
5. Diagram 5 shows an egg placed in two different liquid.
Based on the statements or quations below, identify the steps in the scientific investigation.
(a) Why does the eggsink in water but float in the salt solution?
(b) Density of water/salt solution, density of the eggs,volume of water,type of eggs
(c) Buoyancy of the egg is affected by the liquid used.
(d)
Liquid
Water
Salt solution
Buoyancy of the egg
6. Study the following statements.
Green bean seeds in dry gunny sacks do not germinates
(a) Suggest one hypothesis to investigate the above statements
(b) Described an experiment to test your hypothesis in 6(a) based on the following criteria:
(i)
Aim of the experiment
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(ii)
Identification of variables
(iii)
List apparatus and materials
(iv)
Procedure or method
(v)
Tabulation of data
(vi)
Conclusion
CHAPTER 2: Body Coordination
1. Student A sits on a chair as shown in Diagram 1.
Student B knocks the knee of student A with a ruler.
(a) What can be observed?
(b) Draw an arrow ( ) in Diagram 1 to show the direction of his leg movement.
(c) What inference can be made from your observation in 1(a).
(d) Name the nervous system which controls this action.
2. Diagram 2 shows that the rays of a torch are directed to the eye of a student.
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(a) Draw the pupil of the student in diagram 2(b) after the rays of the torchlight are directed into his eye.
(b) What happens to the pupil?
(c) What inferences can be made from your observations.
(d) Name the type of action that occurs.
3. Diagram 3 shows a type of nerve cell in humans.
(a) What the nerve cell.
(b) What is the function of this nerve cell?
(c) Label structures P, Q, and R.
(d) Draw an arrow ( ) to show the direction on impulse transmission.
(e) Where is the location of structure S?
4. Diagram 4 shows the reflect arc of a reflect action when a person finger is pricked by a needle.
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(a) Name the parts labeled P, Q and R.
(b) What is the function of the structure labeled Q?
(c) Mark the direction of the impulse transmission during the reflect action in Diagram 4.
(d) What happens to structure R when a student’s finger is pricked by a needle?
(e) Which part of the nervous system controls this action?
(f) State one other example of a reflect action.
(g) What is the importance of a reflect actions to us.
5. Diagram 5 shows a longitudinal section of the human brain.
(a) Name the parts labeled P and Q.
(b) State the function of part Q.
(c) Part X controls the body balance. Mark X in the Diagram 5.
(d) Why is the surface of P folded?
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(e) What happens to a person if he experiences injury to parts R and S?
(f) State the part that protects the human brain from injury.
(g) State one example of activity controlled by part P.
6. Diagram 6 shows the locations of three endocrine glands in the body of a male.
(a) (i) name the endocrine gland labeled X.
( ii) State one function of the hormone secreted by gland X.
(b) (i) What happens to the blood of a person if gland Y secretes too little hormone.
( ii) Name the disease which a person may suffer from if the condition you stated in 6(b)(i).
(c) State two effects is both glands Z are removed.
7. Study the following statement.
Reflect action will happen when the light was torched into eyes.
(a) Suggest one hypothesis to investigate the above statement.
(b) By using torch, describe an experiment to test your hypothesis in 7(a) based on the following criteria:
i. Aim of the experiment
ii.
Identification of variables
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iii.
List of apparatus and materials
iv.
Procedure and method
v.
Tabulation of data
vi.
Conclusion
8.
a. State four differences between the nervous system and the endocrine system.
b. An adults realize that his urine contains sugar. Explain how he overcomes his health problem. Your
explanation should include the following aspects:
( i) Identify the problem
( ii) Explain the problem
( iii) Explain the method to solve the problem
( iv) Suggest a daily diet
9.
(a) State four differences between voluntary action and involuntary action.
(b) Diagram 9 shows the actions happen inside the body of a student.
Study the action above. Explain how you can build a concept according to the above information.
Your answer should be based on the following aspects.
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(i) Identify two common characteristic
(ii) Construct the initial concept
(iii)Give one other example and non-example
(iv) Explain the actual concept.
CHAPTER 3 : Heredity and Variation
1. The height of student in a class is measured. The data obtained is shown below.
(a) Based on the data given,complete Table 1.
Heigh of student / cm
Number of student
146 – 150
151 – 155
156 – 160
161 – 165
166 – 170
Table 1
(b) Using the data in Table 1, draw a histogram on the graph paper below.
(c) Based on the graph in 1(b), state the type of variation shown by the height characteristic.
(d) A part from body height, what other characteristic in human that shows the same variation.
2. Table 2.1 shows the types of ear lobe of 20 students in a class.
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(a) Based on the data in Table 2.1, complete Table 2.2.
Number of student with
Attached ear lobe
Free ear lobe
Table 2
(b) Based on the Table 2.2, draw a bar chart in the graph paper below.
(c) What type of variation is shown in the bar chart in 2(b)?
(d) Apart from types ear lobes, state two characteristics in humans that show the same type of variation.
(e) What is the factor that influences variation in 2(c)
3. Diagram 3 shows a cross – breeding between a pea plant with red flowers and a pea plant with white
flowers to produce Fi generation plants. The gene of the red flowers is dominant, while that of the white
flowers receive.
(a) What type of cell divison takes place during the formation of gametes?
(b) Complete the schematic diagram in Diagram 3 to show the cross – breeding between the plants.
(c) State the colour of the flower produce in Fi generation
(d) State the parts of the flower that produce the male gamete and the female gamete.
(e) If the Fi generation plants cross – bred among themselves, predict the ratio of the number of plants
with red flowers to the number of plants with white flower produced.
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4. Diagram 4 shows a part of the cell division which takes place in the human somatic cell.
(a) Name the process of the cell
(b) Complete the stage X in Diagram 4.
(c) State two reasons for the importance of this cell division.
(d) State two sections in plants that experience this cell division.
5. Diagram 5 shows some stages of division occurring in humans.
(a) (i) What type of cell division is this.
( ii) Give a reason for your answer in 5(a)(i)
(b) What happens at Stage L?
(c) Name two organs in humans where this cell division occurs.
(d) State one reason for the importance of this cell division.
(e) State two section in plants which experience this cell division.
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6. Diagram 6 shows a schematic diagram concerning the determination of sex in a child.
(a) Complete the Diagram 6.
(b) Name Process A.
(c) Name the gametes produced by the father and the mother.
(d) What are the saxes of child P and child Q.
(e) What is the probability of having a male child at each birth.
7. Study the following statement.
The height of students is a continues variation.
(a) Suggest one hypothesis to investigate the above statement.
(b) Describe an experiment to test your hypothesis in 7(a) based on the following criteria:
(i) Aim of the experiment
(ii)
Identification of the variables
(iii)
List of apparatus and materials.
(iv)
Procedure and method
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(v)
Tabulations of data
Tabulation :
(vi)
Conclusion.
8.
(a) Explain is occurences of identical twins and non – identical twins.
(b) A student is left-handed but both his parents are right – handed. It is known that the left – handed
respectively, explain how this student endow left – handed genes from his parents. Your explanation
should include the following aspects:
( i ) Identify the problem
( ii) Explain the problem
( iii) Use a schematic diagram to support your answer.
9.
(a) State four differences between mitosis and miosis.
(b) Diagram 9 shows the parts of a student’s body that undergo a type cell division.
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Skin
Nail
Cell
division
Liver
Bones
Diagram 9
Study the body parts where cell division happen. Explain how you can build a concept based on the
information above. Your explanation should include the following aspects:
( i) Identify two common characteristic
( ii) Construct the initial concept
( iii) Give one other example and one non – example in relation to the concept
( iv) Explain the actual concept.
CHAPTER 4 : Matter and Substance
1. Diagram 2 shows the arrangement of apparatus for the process of distillation.
(a) State two mistakes in the arrangement of apparatus shown in Diagram 2.
(b) What is collected in beaker X?
(c) What is the reading of thermometer at that time in (b)?
(d) State the function of the porcelain chips.
(e) State two changes in states of matter during the distillation process.
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2. Diagram 3 shows the arrangement of apparatus used to study heat conductivity.
The time taken for the thumbtack to drop from the metal rod is recorded in Table 3.
(a) Based on the results in Table 3,arrange the sequence of the heat conductivity of metal rod
K,L and M in descending order.
(b) State the variables in this experiment.
i. Constant :
ii. Manipulated :
iii. Respond :
(c) What the hypothesis can be made from this experiment?
(d) If the metal rod used in this experiment are copper,iron and aluminium,identitiy metal rods
K,L and M that represent them.
3. Table 4 shows the melting point,boiling point and electrical conductivity of three types
of substance K,L and M.
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(a) i. Which substance possesses properties of ionic substance?
ii. Give a reason for your answer in 4(a)(i).
(b) i. Which substance is a molecular substance?
ii. Give a reason for your answer in 4 (b)(i).
(c) Why is it that substance M cannot conduct electricity in a solid state?
(d) Why is it that substance L can conduct electricity in both solid and liquid states?
(e) Why does substance K have very low melting and boiling points?
5. Diagram 5 shows the structure of an atom of the helium element.
(a) What are the proton number and nucleon number of helium?
(b) Complete Table 5 to differentiate between proton,neutron and electron.
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(c) Name the group in which helium is located in the Periodic Table.
(d) What is the special characteristic of helium?
6. Table 6 shows the proton number,number of electrons,nucleon number and number of
neutrons of atoms P,Q,R and S.
Particle
P
Q
R
S
Proton Number
3
4
6
6
Number of electrons
4
3
6
6
Nucleon number
7
9
12
13
Number of neutrons
4
6
atom Q and S.
(b) i. Which of these particles is a positive ion?
ii. Give a reason for your answer in 6 (b)(i).
(c) i. Determine one particle which is a neutral atom.
ii. Give a reason for your answer in 6 (c)(i).
(d) i. Which of the particles are isotopes of the same element?
ii. Give a reason for your answer in 6 (d)(i).
7. Diagram 7 shows a part of the Periodic Table.
(a) How are the elements arranged in the Periodic Table?
(b) Determine the element that is
i. the most reactive :
ii. not reactive :
(c) What is the proton number of elelment P?
(d) Element P has a nucleon number orf 19.How many neutrons are there in element P?
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(a) Complete
Table 6 by
writing down
the number of
neutrons for
(e) Among these elements,which is
i. an atomic substance :
ii. a molecular substance :
(f) State two elements which will form an ionic substance when combined.
(g) Which element has the most protons?
7. Study the following statement.
There is a difference in the melting points of atomic and
molecular substances
(a) Suggest one hypothesis to investigate the above statement.
(b) i. Aim :
ii. Variable that :
iii. List of apparatus and materials :
iv. Procedure :
v. Tabulation of data :
vi. Conclusion :
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8. (a) Four differences between ionic substance and molecular substance
(b) Four differences between metals and non-metals.
Metal
Non-metal
CHAPTER 5 : Energy and Chemical Changes
1. Diagram 1 shows the arrangement of apparatus used to determine the reactivity of metals
with oxygen
The results of the experiment are shown in Table 1.
Metal
Aluminium
Znc
Reactivity of metal with oxygen
Aluminium lights up brightly
Zinc glows with a bright flame
(a) Complete Table 1.
(b) Write one inference based on the observation in the experiment.
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(c) State the variables in this experiment.
i. Constant :
ii. Manipulated :
iii. Respond :
(d) What is the function of potassium manganate(VII) crystals?
(e) What is the function of the glass wool in this experiment?
(f) Why do metal filings need to be heated first before the heating of potassium manganate
(VII) crystals?
(g) Based on your observation,arrange the reactivity of the three metals in decreasing order.
2. Diagram 2 shows the arrangement of apparatus to study the purification of metal.
The experiment is repeated a few times with different quantities of electric current.The cathode is cleaned,dried
and weighed after 10 minutes for each experiment.The results obtained are recorded in Table 2.
Electriccurrent/C
Mass of cathode/g
300
1.05
600
1.10
900 1200
1.15
1500
1.25
1800
1.30
2100
1.35
(a) In Diagram 2,mark the positive electrode(anode) with the symbols ‘+’.
(b) Draw a graph showing the quantity of electric current versus the mass of cathode.
(c) From the graph drawn,determine the mass of the cathode when the quantity of electric
current is 1200C.
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(d) Based on the graph in 2(b),what is the relationship between the quantity of electric current
and the mass of cathode?
3. Diagram 3 shows an experiment that is conducted to study the reaction between zinc and
hydrochloric acid.
The volume of hydrogen gas that is released is recorded every 30 seconds.The results obtained are recorded in
Table 3.
Time/second
Volume of hydrogen gas/cm³
0
0
30
25
60
38
90
46
120
50
150
50
180
50
(a) Based on Table 3,draw a graph of the volume of hydrogen gas against time.
(b) Based on the graph drawn in 3(a),state the relationship between the volume of gas and time
in the first 90 seconds.
(c) State the variables in the experiment.
i. Manipulated :
ii. Respond :
iii. Constant :
(d) Predict the volume of hydrogen gas that is collected at 210th second.
(e) Give one other metal that can be used to replace zinc in this experiment.
4. Diagram 5 shows the arrangement of apparatus for the electroplating of an iron nail with copper plate.
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(a) Name the process occurred.
(b) What the material is used as :
i. anode :
ii. cathode :
(c) Suggest one electrolyte that can be used to replace copper(II) sulphate solution.
(d) State what can be observed of the following materials at the end of the experiment.
i. Copper plate :
ii. Iron nail :
(e) Write the energy transformation that occurs in this process.
(f) State two other uses of the process mentioned in 5 (a).
5. Diagram 6 shows a model of a simple voltaic cell.
(a) What can be observed on the voltmeter?
(b) Give an inference to the observation in 6(a).
(c) Write the energy transformation that occurs in this experiment.
(d) i. What will happen if the copper plate is replaced with a carbon card?
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ii. Give a reason for your answer in 6(d)(i).
(e) State one example of a food item which can be used to replace vinegar solution.
6. Diagram 7 shows the experiment to study the reaction of sodium with water.
(a) What happens to the sodium?
(b) Name the gas released when sodium reacts with water
(c) i. What can be observed if a few drops of phenolphthalein indicator are dripped into
the basin?
ii. Give the property of the solution formed.
(d) Write one chemical equation in words for the reaction that occurs between sodium and
water.
7. Diagram 8 shows a piece of photographic paper.The centre section is covered with a
round piece of black paper and exposed to sunlight for one minute.
(a) Draw your observation at the end of the experiment.
(b) What is the layer that covers the photographic paper?
(c) What happens to the layer you mentioned in 8(b) when it is exposed to sunlight?
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(d) Write an equation in words to explain the occurrence in 8(c).
8. Study the following statement.
Electrical energy can be produced from fruit
(a) Suggest one hypothesis to investigate the above statement.
Hypothesis :.
(b) i. Aim :
ii. Variable that
- Constant :
- Manipulated :
- Respond :
iii. List of apparatus and materials :
iv Procedure :
v. Tabulation of data :
vi. Conclusion
9. (a) State one method that can be used to plate the iron chain with the copper.
10. (a) Diagram 11.1 shows the addition of potassium iodine solution to the lead(II) nitrate
solution.
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State four reasons why the above reaction is considered to be a chemical change.
(b) Diagram 11.2 shows the physical changes in different substances.
i. - The shapes of the substances are changed.
ii. Initial concept :
iii. Example
Non-example
iv. Actual report :
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CHAPTER 6 : Nuclear Energy
SECTION B
1. Diagram 1 shows the deflection of radioactive radiation.
(a) What are radiation X,Y and Z?
X : Alpha
Y : Gamma
Z : Beta
(b) Why does ray Y not deflect?
Ray Y not deflected because its neutral in terms of electrical charges.
(c) i. Which ray can be blocked by only a sheet of paper?
Ray X
ii. Give an inference for your answer in 1(c)(i).
Ray X because the penetrating power is low.
(d) What is the best way to store radioactive substances?
Store in thick lead containers surrounded by thick concretes.
(e) i. Which ray is the most dangerous?
Ray Y.
ii. Explain your answer in 1 (e)(i).
Ray Y because the penetrating power is high.
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2. Diagram 2 shows the generation of electrical energy from a nuclear reactor.
(a) What processes take place at stages A,B and C?
A : Nuclear energy is produced by nuclear fission of uranium in a nuclear reactor.
B : Nuclear energy is converted to heat energy and boils water to produce steam.
C : Steam under high pressure rotates the turbine and generates electricity in the
generator.
(b) State the energy transformation that takes place during generation of electrical energy.
Nuclear energy
heat energy
kinetic energy
electrical energy
(c) Give two effects if nuclear energy is misused.
Explosion and pollution occur.
3. Diagram 3 shows the use of a radioactive substance in detecting a leak in an underground
water pipe.
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(a) State briefly how the work in Diagram 3 can be done?
- A small quantity of radioactive substance is put into water,gas/oil in an underground
pipe.
- The movement of the radioactive substance can be traced by using the Geiger-Muller
Counter.
(b) State two other uses of radioactive substances.
i. Medicine : kill cancer cell
ii. Food preservation : sterilising food
(c) Name one material which can be used to stop beta radiation.
Thin aluminium plate
(d) State two adverse effects of radioactive rays to human beings.
- Mutation
- Cancer
SECTION C
4. (a) State four differences between alpha and beta rays.
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Alpha rays
Nucleus of helium
Positive charge
Low penetrating power
Can be blocked by a sheet of paper
Beta rays
High speed electrons
Negative charge
High penetrating power
Can be blocked by a thin sheet of aluminium
(b) i. Problem statement :
- Protecting from radioactive rays
- Storing radioactive substance in proper way
ii. Safety measures :
- Wearing a special protective outfit
- Wearing a film badge
iii. Method of storage :
- Store in thick lead containers
- Surrounded by a thick concrete
5. (a) Compare isotopes and radioisotopes by using examples of carbon-12 and carbon-14.
Similarity : Both have the same number of proton
Number of electrons
Number nucleon
Carbon-12 Isotopes
6
12
29
Carbon-14 Radioisotopes
8
14
Emits radioactive radiation
No
Yes
(b) Study the information and build a concept of beta rays.
i. Identify the information :
- Beta rays deflect to positive plate
- Beta rays can penetrate through a paper but cannot penetrate through a thin
aluminium sheet.
ii. Explain the information :
- Beta rays are negatively charged
- The penetrating power of beta rays is moderately high
iii. Initial concept : Beta rays are negatively charged and have a high penetrating
power
iv. Example : Can penetrate through thin plastic
Non-example : Cannot penetrate through thin plastic
v. Actual concept : Beta rays are rays with negative charge and have a moderately
high penetrating power.
CHAPTER 7: Light, Colour and Sight
SECTION A
1. Diagram 1.1 shows a part of the light rays on a plane mirror.
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(a) Complete Diagram 1.1 by drawing the light rays reaching the observer’s eye.
(b) What is the relationship between distances X and Y?
X and Y are same distance
(c) State two characteristics of the image formed.
Virtual and upright
(d) In Diagram 1.2,draw the image formed on the plane mirror.Then,state the characteristic
of that image.
Characteristic of image : Inversed laterally
2. Diagram 2.1 shows an object placed in front of a pinhole camera.
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(a) In Diagram 2.1,draw a ray diagram to show the image formed on the screen.
(b) State two characteristics of the image formed.
Real and inverted
(c) What is the effect to the image if
i. The size of the pinhole is enlarged?
More bright but blur.
ii. A convex lens is placed between the object and the pinhole?
The image will be more sharper.
iii. The pinhole camera is moved towards the object?
The image will be more bigger.
(d) Two more pinholes are punched in the camera as shown in Diagram 2.2.Draw and
label the image formed.
3. Diagram 3 shows a 0.7cm high object placed in front of a convex lens.
(a) Complete the ray diagram to show the formation of an image in Diagram 3.
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(b) What is the height of the image formed?
0.7 cm
(c) State two characteristics of the image formed.
Real and inverted.
(d) What optical instrument possesses the object distance of 2F?
Photocopy machine
(e) Why can’t the location of the image be determined if the object is less than the
focal length of the lens,F?
The image is virtual.
4. Diagram 4 shows an experiment carried out to determine the focal length of
different convex lens.
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(a) Measure the focal length of the convex lenses in Diagram 4 and write down their
focal length in Table 4.
Thickness of the convex lens
Thin
Thick
Focal length (cm)
3.6 ± (0.1)
2.4 ± (0.1)
(b) What is the inference that can be made for this experiment?
The thicker the thickness of the convex lens,the shorter the focal length.
(c) State the variables involved in this experiment.
i. Manipulated : The thickness of convex lens
ii. Respond : The focal length
iii. Constant : Light ray from distant object
(d) State the hypothesis for this experiment.
When the thickness of convex lens increases,The focal length will be decreases.
5. Diagram 5.1 and Diagram 5.2 show the experiment that is carried out to study the
image formed by a pinhole camera.
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(a) Draw the light rays in Diagram 5.1 and Diagram 5.2 to show the formation of image.
(b) Measure the size of the image formed in Diagram 5.1 and Diagram 5.2.
i. Size of image in Diagram 5.1 : 0.4 ± (0.1 cm)
ii. Size of image in Diagram 5.2 : 0.5 ± (0.1 cm)
(c) State the variables involved in this experiment.
i. Manipulated : Distant of object
ii. Respond : Size of image formed
iii. Constant : Size of the object
(d) What is the hypothesis that can be made in this experiment?
When the distance of the object from the pinhole camera decreases,the size of image
will increases.
(e) State two characteristics of the image formed in this experiment.
Real and inverted.
(f) Predict the size of the image formed if the object is placed 15 cm from the pinhole.
Less than 0.4 cm
SECTION B
6. Diagram 6.1 shows the arrangement of apparatus used to study light dispersion.
35
(a) i. What happens to the white lights at the border of the prism?
Refracted
ii. Give a reason for your answer in 6(a)(i)
It is because the white light are refracted from one medium to another with
different densities or angles.
(b) What is the colour of the light formed at P and Q on the white cardboard?
P : Red
Q : Violet
(c) Complete the boxes below to show the sequence of colours formed in the spectrum.
P(Red),Orange,Yellow,Green,Blue,Indigo,Q(Violet).
(d) A similar prism is palced in the position as shown in Diagram 6.2.
i.
What can be observed on the white cardboard?
White light.
ii. State one natural phenomena in which a spectrum can be seen.
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Formation of rainbow.
7. Diagram 7 shows the structure of a camera.
37
(a) Label structure X and Y.
X : Diaphragm
Y : Film
(b) Name the structures of the human eye which are analogous to structures X and Y.
X : Iris
Y : Retina
(c) What is the function of X in the camera?
Controls the size of aperture and amount of light that enters to the camera.
(d) How can a sharp image be focused in a camera?
The lens focuses the image of an object onto the film.The lens is adjusted by the
focus adjuster either towards or away from the film to obtain a sharp image.
8. Diagram 8 shows the formation of a rainbow after an evening rain.
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(a) How is a rainbow formed?
- Sunlight shines on the raindrop.
- A part of the light is reflected off the outer surface of the raindrop.
- A part of the light is refracted at the different angles in the raindrop.
- The light is split into its colour constituents through dispersion.
- The colour constituents are reflacted off the far inner surface of the raindrop.
- Light refraction occurs again as it exits the raindrop.A rainbow is formed.
(b) What is the role of the raindrops?
Act as a prism.
(c) State two processes that occurred to the sunlight at X?
Dispersion and refracted.
(d) What process occurs to the sunlight at Y?
Reflected
9. Diagram 9 shows the arrangement of apparatus to study the addition of coloured light.
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(a) What colours are formed in the regions of X,Y and Z?
X : Red
Y : Magenta
Z : Blue
(b) i. Of the colours formed on the screen,which is the secondary colour?
Magenta.
ii. Give a reason for your answer in 9(b)(i).
Magenta can only be produced from addition of two primary colours,blue and red.
(c) What coloured light is formed in region X if a yellow filter is placed in front of the
red filter in torch P?
Red.
(d) What coloured light is formed in region Z if a green filter is placed in front of the
blue filter in torch Q?
No colour formed.
(e) If a piece of cyan cloth is placed under the light rays in region Y,what colour will the
cloth appear as?
Blue.
SECTION C
10. Study the following statement.
40
The spectacles of old people have shorter focal length than those of a student who is
long-sighted.This is because the lenses in their spectacles have a different thickness.
(a) Suggest one hypothesis to investigate the above statement.
Hypothesis : The thicker a lens,the shorter its focal length.
(b) i. Aim : To estimate the focal length of a convex lens and relate it to the thickness of
the lens.
ii. Variable that :
- Constant : Object distance
- Manipulated : Thickness of the lens
- Respond : Focal length
iii. List of apparatus and materials : Metre ruler,screen,convex lenses with vary
thickness,lens holder.
iv. Procedure :
- The arrangement of apparatus is set up as shown in the diagram below,facing an
object outside the window.
- The screen is adjusted until a sharp image is formed on it.
41
- The focal length is measured with a metre ruler.
- The experiment is repeated using lenses of different thickness.
v. Tabulation of data :
Thickness of the lens
Thin
Thick
Focal length, f/cm
vi Conclusion : A thick convex lens has a short focal length while a thin convex lens has
a long focal length.
11. (a) Contrast the mechanism of focusing and the mechanism of controlling the amount
of light entering the human eye and the camera.
Mechanism of focusing :
- Eye : Focussing is done when thickness of the lens is regulated by the ciliary
body.
42
- Camera : Focussing is done by regulating the distance between the lens and
the film.
Mechanism of controlling the amount of light :
- Eye : The amount of light entering the eyes is controlled by the iris.
- Camera : The amount of light entering the camera is controlled by the
diaphragm.
(b) Explain how the student can build one device to solve his problem.
i. Problem statement : Seeing an object behind the wall.
ii. Name of the device : Periscope
iii. Name of the light principle that applied : Reflection
iv. Step in building the device :
- Two plane mirrors are arranged parallel to one another at an angle of
45º.
- Light rays from the first mirror are incident to the surface of the second
mirror.
- The second mirror reflects the light rays to the eyes of the student.
12. (a) Compare the images formed by a concave lens and a magnifying glass.
- The images formed by a concave lens and a magnifying glass are virtual
and upright.
- A magnifying glass forms a bigger image than the object.
(b) Diagram 12 shows the colours that appear in the screen when white light is passed
43
through the coloured filters.
i. Identify the problem :
- A red filter only allows green light to pass through it.
- A green filter only allows green light to pass through it.
ii. Identify two common characteristics :
- Red and green coloured filters only allow their own colours to pass
through them.
- Other colours are absorbed by red and green coloured filters.
iii. Initial concept :
Red and green coloured filters only allow their own colours to pass through
them but absorb other colours showing that they are primary colours.
iv. Example : Blue
Non-example : Yellow,cyan,magenta
v. Actual concept :
Primary filters only allow their own colours to pass through them but absorbed
other colours.
44
CHAPTER 8 : Chemicals in Industry
SECTION A
1. Diagram 1 shows that a steel ball is attached to the surface of a pure copper block with cellophane tape.
A weight is dropped on atop of the copper block from a height of 50 cm. The diameter of dent formed is
recorded. The experiment is repeated with a bronze block. Table 1 shows the result of the experiment.
45
Ex periment
Diameter of dent on pure copper block/mm
Diameter of dent on bronze block/mm
Average diameter of dent/mm
4.2
3.8
Table 1
(a) Based on the results on the experiment, which block is harder?
Bronze block.
(b) What is relationship between the diameter of dent formed and the hardness of metal or alloy?
The smaller the diameter of the dent formed, the harder is the metalor alloy.
(c) What hypothesis can be made from this experiment?
The diameter of a dent formed on the pure copper block is bigger.
(d) State the variable that
(i)
Is kept constant
Height of the weight.
(ii)
Is manipulated
Type of block
(iii) Respond
Diameter of dent.
(e) Define alloy operationally based on the results of the experiment.
Alloy is a material in which the depression produced on it is smaller.
2. Diagram 2 shows the experiment to study the rusting of metals.
Both test tubes with their contents are left for three days. The results are recorded in Table 2.
Type of nails
Iron nail
Stainless steel nail
Observations
Rust
46
Table 2
(a) Complete Table 2 by showing what has happened to the stainless steel nail at the end of the
experiment.
Does not rust.
(b) Which nail is more resistant to corronsion?
Stainless steel nail.
(c) State the variable
( i ) is kept constant : Volume and concentration of sodium chloride solution.
( ii) is manipulated : Type of nail.
( iii) responds :Rusting of the nail.
(d) Define alloy operationally based on the observation of the experiment.
Alloy is a material which does not rust.
SECTION B
3. Brass and steel are two examples of alloy.Brass which consists of copper and another
element is harder than pure copper.
(a) What element is mixed with copper to form brass?
Zinc.
(b) What type of particles is found in pure copper?
Atom.
(c) Draw and label the arrangement of particles in pure copper and in brass.
47
(d) Explain why brass is harder than pure copper.
The atoms in pure copper are the same in size and are packed closely.Layers of these
atoms easily slide over one another when force is applied.The zinc and copper atoms
in brass are of different sizes.This disrupts the arrangement of the layers of atoms
and make them difficult to slide over one another.
(e) State the pure metal and foreign atoms that form steel.
Pure metal : Iron
Foreign atom : Carbon
4. Diagram 4 shows the disposal of industrial waste from a chemical factory that
manufactures chemicals needed for the growth of crops.
(a) State one product that could be produced by the factory.
Fertiliser.
(b) State two pollutants that might be disposed from the factory into the river.
48
Nitrate and phosphate compounds
(c) State one adverse effects of the pollutants in 4(b) on the environment.
Disrupt the balance of aquatic ecosystem.
(d) The factory uses petroleum as the source energy.
i. State one acidic gas produced in the burning of fossil fuel.
Sulphur dioxide
ii. State one method to control air pollutant in 4(d)(i) from the factory.
Dissolve the gas using air cleaner system before release to air.
5. Air pollution is caused by the burning of fossil fuel from factories.
(a) Give three examples of pollutants which may be contained in the smoke released
from factory chimneys.
Carbon monoxide,dust and sulphur dioxide.
(b) i. What happens if acidic gas dissolves in rain water?
Acid rain.
ii. State one effect of pollution to the environment and human health caused by the
event in 5(b)(i).
Environment : Lower pH value
Human health : Respiratory system
(c) Suggest one way how factories can reduce the release of acidic gas into the air.
49
Dissolve the gas using air cleaner system before release to air.
(d) Apart from factories,what other source that causes poisonous gases to be releases to the
surroundings?
Motor vehicles
SECTION C
6. Study the following statement.
Iron nails left outside the house rust
compared to stainless steel nail.
easily
(a) Suggest one hypothesis to investigate the above statement.
Hypothesis : A stainless steel nail does not rust easily compared to an iron nail.
(b) i. Aim : To study the resistance of stainless steel nail to rusting.
ii. Variable that :
- Constant : Concentration and volume of sodium chloride solution.
- Manipulated : Type of nail
- Respond : Rusting of nail
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iii. List of apparatus and materials : 0.5 mol dm‾³ sodium chloride solution,iron nail,
stainless steel nail,test tubes,test tube rack.
iv. Procedure :
- Test tubes A and B are each filled with 5 cm³ of sodium chloride solution.
- An iron nail is put into test tubes A and stainless steel nail into test tube B.
- Both test tubes are left on a rack for three days.
- Observation of the nails is recorded.
v. Tabulation of data :
Type of nail
Iron nail
Stainless steel nail
vii.
Observation
Conclusion : Alloy is more resistant to rust than pure metal.
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7. (a) State one process that can be used to produce this chemical substance.Explain.
- Haber process
- One volume of nitrogen and three volumes of hydrogen are used.
- Temperatures between 450-500 °C and 200-500 atmosphere pressure.
- Iron filings are used as the catalyst.
(b) Explain how he can prepare ammonia fertilizer by using the following substances.
i. Ammonium sulphate
ii. Crystallisation
iii. - Excess ammonia solution is added to sulphuric acid.
- The mixture is heated until saturated.
- The solution is left to cool.
- Ammonium sulphate crystals are produced.
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8. (a) State four differences between bronze and copper.
Bronze
Mixture of copper and tin
Harder
Stronger
Can withstand corrosion
Copper
Consists of copper only
Softer
Less strong
Cannot withstand corrosion
(b) i. Identify the common characteristics :
- Contain two or more metals
- Stronger than pure metals
ii. Initial concept : Substance that contains two or more metals and is stronger
compared to pure metals is an alloy.
iii. Example : Bronze
Non-example : Tin
iv. Actual concept : Alloy is a substance that contains two or more metals and is
more stronger compared to pure metals.
53
54
CHAPTER 1 : Scientific Investigation
SECTION A
7. Study the following section
Iron nails rust easily when left outside the house.
(d) What the problem that can be identified?
Why iron nails rust easily when left outside the house.
(e) Make one hypothesis for the situation given.
Water is needed for rusting the nails.
(f) Identify the following variables:
8. Variable that is constant
Type of irons.
9. Variable that is manipulated
Presence of water.
10. Variable that responds
Rusting of iron nails.
11. Diagram 2 shows the arrangement of apparatus to studt the relationship between the
55
Length of the thread and the duration of the swing of the pendulum.
(e) What are the variables involved in this experiment?
(iv)
Variable that is constant.
Number of swings
(v)
Variable that is manipulated.
Length of thread
(vi)
Variable that responds.
Time taken for apendulum swing.
(f) What is the relationship between the length of the thread and the duration of the swing of the
pendulum.
The longer the thread, the longer the time taken for a pendulum to swing.
(g) If the height of the pendulum from the surface of the table is increased, predict the time taken for the
pendulum to swing.
Time taken by the pendulum to swing is shorter.
(h) State one precautionary step when conducting this experiment.
Carry out the experiment in area of calm air.
56
12. An experiment is conducted to study the relationship between the force (N) and the extension of a spring.
The results are shown in Diagram 3.
(e) State the variable:
(iii) That is manipulated
Force
(iv)
That responds
Extension of the spring.
(f) What is the relationship between the forces (N)and the extansion of the spring (cm)?
The grater the force applied, the more the spring lengthens.
(g) Study Diagram 3 and fill the data in the table below.
Force/N
Extansion of the spring/cm
1
2
2
4
3
6
(h) Predict the extension of the spring if a force of 6 N is applied.
12 cm
SECTION B
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4
8
5
10
13. Diagram 4 shows a part of the steps in a scientific investigation.
Identifying a problem
Making a hypothesis
Identifying the
variables
Cotrolling
the variables
x
Diagram 4
(f) How can problem be identify?
Always observe phenomena or occurrences that happen in the surroundings.
(g) What is variable
A condition or factor which can be changed in a scientific investigation.
(h) State three variables in a scientific investigations
Variables that are kept constant, manipulated and responds.
(i) What should be done if the hypothesis made is not accepted by the experiment?
A new hypothesis is made.
(j) Identify step x in the scientific investigation.
Plan the investigation.
14. Diagram 5 shows an egg placed in two different liquid.
58
Based on the statements or quations below, identify the steps in the scientific investigation.
(e) Why does the eggsink in water but float in the salt solution?
Identifying the problem
(f) Density of water/salt solution, density of the eggs,volume of water,type of eggs
Identifying the variables.
(g) Buoyancy of the egg is affected by the liquid used.
Making a hypothesis.
(h)
Liquid
Water
Salt solution
Collecting the data.
Buoyancy of the egg
SECTION C
15. Study the following statements.
Green bean seeds in dry gunny sacks do not germinates
59
(c) Suggest one hypothesis to investigate the above statements
Hypothesis : Seeds need water to germinates.
(d) Described an experiment to test your hypothesis in 6(a) based on the following criteria:
(vii) Aim of the experiment
Aim : To study the need of water for seed germination/
(viii) Identification of variables
Variable that :
 Is kept constant : Type of seed/surrounding /temperature/presence of air
 Is manipulated : Presence of water.
 Responds : Germination of seed.
(ix)
List apparatus and materials
List of apparatus and materials : Seeds, test tube, cotton wool, water
(x)
Procedur or method
Procedure :




(xi)
Seeds are put into two test tubes.
Water is dripped into second test tube.
Test tubes are left for two days.
Observation of the seed germination is recorded.
Tabulation of data
Condition of cotton wool.
Dry
Soaked
Germination of seeds.
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(xii)
Conclution
Germination of seeds requires
CHAPTER 2: Body Coordination
SECTION A
11. Student A sits on a chair as shown in Diagram 1.
61
Student B knocks the knee of student A with a ruler.
(e) What can be observed?
(f) Draw an arrow ( ) in Diagram 1 to show the direction of his leg movement.
(g) What inference can be made from your observation in 1(a).
Knee – jerking is a reflect action.
(h) Name the nervous system which controls this action.
Spinal cord.
12. Diagram 2 shows that the rays of a torch are directed to the eye of a student.
62
(e) Draw the pupil of the student in diagram 2(b) after the rays of the torchlight are directed into his eye.
(f) What happens to the pupil?
The pupil constricts.
(g) What inferences can be made from your observations.
Pupils constrict to prevent excessive light entering the eyes.
(h) Name the type of action that occurs.
Reflex action.
SECTION B
13. Diagram 3 shows a type of nerve cell in humans.
(f) What the nerve cell.
Motor neurone
63
(g) What is the function of this nerve cell?
Transmits impulses from central nervous system (brain or spinal cord) to effector (muscle or gland)
(h) Label structures P, Q, and R.
P- Cell body
Q- Dendrite
R- Myelin sheath
S-Nerve ending
(i) Draw an arrow ( ) to show the direction on impulse transmission.
(j) Where is the location of structure S?
Effector.
14. Diagram 4 shows the reflect arc of a reflect action when a person finger is pricked by a needle.
(h) Name the parts labeled P, Q and R.
P- Synapse
Q-Receptors / Sensory organ
R-Muscles/ Effectors
64
(i) What is the function of the structure labeled Q?
Responds to the stimulus. Nerve impulse is triggered.
(j) Mark the direction of the impulse transmission during the reflect action in Diagram 4.
(k) What happens to structure R when a student’s finger is pricked by a needle?
Contracts.
(l) Which part of the nervous system controls this action?
Spinal cord.
(m) State one other example of a reflect action.
Finger jerks away when it touches a hot kettle.
(n) What is the importance of a reflect actions to us.
To avoid danger or injury.
15. Diagram 5 shows a longitudinal section of the human brain.
(h) Name the parts labeled P and Q.
P-Cerebrum
Q-Medulla oblongata
65
(i) State the function of part Q.
Controls involuntary action,
(j) Part X controls the body balance. Mark X in the Diagram 5.
(k) Why is the surface of P folded?
To increase surface area for the placement of more neurons
(l) What happens to a person if he experiences injury to parts R and S?
R-Deaf
S-Blind
(m) State the part that protects the human brain from injury.
Cranium
(n) State one example of activity controlled by part P.
Looking /Thinking / Walking.
16. Diagram 6 shows the locations of three endocrine glands in the body of a male.
(d) (i) name the endocrine gland labeled X.
Thyroid gland
( ii) State one function of the hormone secreted by gland X.
Stimulates growth / control the metabolic rate.
66
(e) (i) What happens to the blood of a person if gland Y secretes too little hormone.
The glucose level increases in his blood.
( ii) Name the disease which a person may suffer from if the condition you stated in 6(b)(i).
Diabetes
(f) State two effects is both glands Z are removed.
Sterile / Sperms cannot be produced / Development of secondary male sexual characteristics are stunted.
Section C
17. Study the following statement.
Reflect action will happen when the light was torched into eyes.
(c) Suggest one hypothesis to investigate the above statement.
Hypothesis – Pupils constrict when light entering the eye.
(d) By using torch, describe an experiment to test your hypothesis in 7(a) based on the following criteria:
viii. Aim of the experiment
Aim – to study the effect of light on pupil
ix.
Identification of variables
Variable that
 Is kept constant : Pupil
 Is manipulated : Light ray
 Responds : Constriction of pupil.
x.
List of apparatus and materials
List of apparatus and materials : torch
67
xi.
Procedure and method
Procedure :
 The ray of torch is directed into the pupil.
 Observation on the change of the size of pupil is recorded.
xii.
Tabulation of data
Tabulation :
Experiment
Light illuminates the eye
xiii.
Condition of pupil
Conclusion
The reflect action causes the pupils to constrict when light entering the eye.
18.
c. State four differences between the nervous system and the endocrine system.
Nervous system
Endocrine system
Impulses is sent through nerve
Impulses is sent through bloodstream
A short-term effect
Long-term effects
Action is specific target areas
Action is wide target areas
Fast and immediate responds
Slow and continuous responds
d. An adults realize that his urine contains sugar. Explain how he overcomes his health problem. Your
explanation should include the following aspects:
( i) Identify the problem
Urines contains sugar.
( ii) Explain the problem
 Less trickle of insulin hormone in his pancreas.
 Blood has less insulin hormones.
 Extra sugar in the blood cannot change into glycogen for storage
( iii) Explain the method to solve the problem
Injection of insulin hormone
( iv) Suggest a daily diet.
Reduce sugar taking in the daily diet.
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19.
(a) State four differences between voluntary action and involuntary action.
Voluntary action
Involuntary action
Controlled by cerebrum
Controlled by medulla oblongata
There is awareness
Unaware
Controlled by somatic nervous system
Controlled by autonomic nervous system
Respond can be faster or slower
Spontaneous action
(b) Diagram 9 shows the actions happen inside the body of a student.
Study the action above. Explain how you can build a concept according to the above information.
Your answer should be based on the following aspects.
(v) Identify two common characteristic
Common characteristic :
 Unaware action
 Action that is controlled by the medulla oblongata
(vi) Construct the initial concept
Initial concept : Involuntary action is an action that react automatically without knowledge
and controlled by the medulla oblongata.
(vii) Give one other example and non-example
Example : Constriction of pupils / Constriction of blood vessels
Non – examples : Listening / Seeing / Writing
69
(viii) Explain the actual concept.
Actual concept : Involuntary action is an action that react automatically without knowledge
and controlled by the medulla oblongata.
CHAPTER 3 : Heredity and Variation
SECTION A
8. The height of student in a class is measured. The data obtained is shown below.
(e) Based on the data given,complete Table 1.
Heigh of student / cm
Number of student
146 – 150
1
151 – 155
156 – 160
8
19
Table 1
161 – 165
9
166 – 170
3
(f) Using the data in Table 1, draw a histogram on the graph paper below.
(g) Based on the graph in 1(b), state the type of variation shown by the height characteristic.
Continuous variation.
(h) A part from body height, what other characteristic in human that shows the same variation.
Skin colour /Body weight.
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9. Table 2.1 shows the types of ear lobe of 20 students in a class.
(f) Based on the data in Table 2.1, complete Table 2.2.
Number of student with
Attached ear lobe
12
Free ear lobe
8
Table 2
(g) Based on the Table 2.2, draw a bar chart in the graph paper below.
(h) What type of variation is shown in the bar chart in 2(b)?
Discontinuous variation.
(i) Apart from types ear lobes, state two characteristics in humans that show the same type of variation.
Blood group and type of fingerprint / left handedness
(j) What is the factor that influences variation in 2(c)
71
Genetic
SECTION B
10. Diagram 3 shows a cross – breeding between a pea plant with red flowers and a pea plant with white
flowers to produce Fi generation plants. The gene of the red flowers is dominant, while that of the white
flowers receive.
(f) What type of cell divison takes place during the formation of gametes?
Meiosis.
(g) Complete the schematic diagram in Diagram 3 to show the cross – breeding between the plants.
(h) State the colour of the flower produce in Fi generation
Red.
(i) State the parts of the flower that produce the male gamete and the female gamete.
Male gamete : Anther
Female gamete : Ovary
(j) If the Fi generation plants cross – bred among themselves, predict the ratio of the number of plants
with red flowers to the number of plants with white flower produced.
3:1.
11. Diagram 4 shows a part of the cell division which takes place in the human somatic cell.
72
(e) Name the process of the cell
Mitosis.
(f) Complete the stage X in Diagram 4.
(g) State two reasons for the importance of this cell division.


Produces new cells for the process of growth.
Produces new cell to replace damaged or dead cells.
(h) State two sections in plants that experience this cell division.
Tip of the root and shoot.
12. Diagram 5 shows some stages of division occurring in humans.
73
(f) (i) What type of cell division is this.
Meiosis
( ii) Give a reason for your answer in 5(a)(i)
Chromotids do not separate at stage M
(g) What happens at Stage L?
Replication or chromosome.
(h) Name two organs in humans where this cell division occurs.
Testis and ovary.
(i) State one reason for the importance of this cell division.
To produce gametes/ Ensure the number of chromosomes is diploid in zygote during fertilization.
(j) State two section in plants which experience this cell division.
Anther and ovary.
13. Diagram 6 shows a schematic diagram concerning the determination of sex in a child.
74
(f) Complete the Diagram 6.
44 + XX
44 + XX
44 + XY
44 + XY
(g) Name Process A.
Meiosis
(h) Name the gametes produced by the father and the mother.
Father : Sperm
Mother : Ovum
(i) What are the saxes of child P and child Q.
P : Female
Q : Male
(j) What is the probability of having a male child at each birth.
50%
SECTION C
14. Study the following statement.
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The height of students is a continues variation.
(c) Suggest one hypothesis to investigate the above statement.
Hypothesis : Height of students in the class.
(d) Describe an experiment to test your hypothesis in 7(a) based on the following criteria:
(i) Aim of the experiment
Aim : Study the height of students in the class.
(vii) Identification of the variables
Variables that
 Is kept constant : Age of students
 Is manipulated : Difference of student
 Responds : Height of students.
(viii) List of apparatus and materials.
List of apparatus and materials : Ruler
(ix)
Procedure and method
Procedure :
 The height of student is measured using the ruler.
 The height of students is recorded.
(x)
Tabulations of data
Tabulation :
150 – 154
Height (cm)
Number of
students
(xi)
155 – 159
160 – 164
170 - 175
Conclusion.
Conclusion : The height of student is a continuous variation because it shows different
value.
8.
(c) Explain is occurences of identical twins and non – identical twins.
Identical twins
 One ovum is fertilized by one sperm
 Zygote that is formed divides into two and forms two zygotes.
Non – identical

165 – 169
Two ova are fertilized by two sperm
76

Two separate zygotes are produces.
(d) A student is left-handed but both his parents are right – handed. It is known that the left – handed
respectively, explain how this student endow left – handed genes from his parents. Your explanation
should include the following aspects:
( i ) Identify the problem
The student is left – handed but both his parents are right –handed.
( ii) Explain the problem
 The student carries kk genes
 Both his parents carry Kk genes.
( iii) Use a schematic diagram to support your answer.
9.
(c) State four differences between mitosis and miosis.
Mitosis
Meiosis
Cell division happens once
Cell division happens twice
Crossing over does not happens
Crossing over happens
Two daughter cells produced
Four daughter cells produced
Number of chromosomes in daughter
Number of chromosomes in daughter
cells in the same as those in parent cell. cells is half of those in parent cell
(d) Diagram 9 shows the parts of a student’s body that undergo a type cell division.
77
Skin
Nail
Cell
division
Liver
Bones
Diagram 9
Study the body parts where cell division happen. Explain how you can build a concept based on the
information above. Your explanation should include the following aspects:
( i) Identify two common characteristic
Common characteristics:
 Cell division involves the formation of new cells.
 Cell division takes place in somatic cells.
( ii) Construct the initial concept
Initial concept : The formation of new cells in somatic cells takes place through
mitosis.
( iii) Give one other example and one non – example in relation to the concept
Example – Heart
Non – Example – Sperm/ovum
( iv) Explain the actual concept.
Actual concept : Mitosis is a cell division process which take place in the somatic
Cells to produce new cells.
CHAPTER 4 : Matter and Substance
SECTION A
1. Diagram 1 shows an experiment to study the effect of impurities on the freezing point.
The result obtained are recorded in Table 1.
Substance
Freezing point/ °C
78
Distilled water
Distilled water + common salt
0
-2
(a) Based on the experiment shown in Diagram 1,complete Table 1.
(b) Write an inference based on the result of this experiment.
Impurities lower the freezing point of the distilled water.
(c) State the variables in this experiment.
i. Constant : Volume of distilled water
ii. Manipulated : Presence of impurities
iii. Respond : Thermometer reading
(d) Based on the experiment,define distilled water operationally.
Distilled water is a substance which has a freezing point of 0 °C
(e) Predict the effect of impurities on the boiling point of distilled water.
Impurities increases the boiling point of distilled water.
2. Diagram 2 shows the arrangement of apparatus for the process of distillation.
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(b) State two mistakes in the arrangement of apparatus shown in Diagram 2.
- The thermometer must not be into the round-bottomed flask.
- The direction of water flow is reversed.
(b) What is collected in beaker X?
Pure water or distilled water.
(c) What is the reading of thermometer at that time in (b)?
100 °C
(d) State the function of the porcelain chips.
- To prevent the liquid mixture in the flask.
- To break the air bubbles when the liquid mixture is boiling.
(e) State two changes in states of matter during the distillation process.
- Boiling
- Condensat
3. Diagram 3 shows the arrangement of apparatus used to study heat conductivity.
The time taken for the thumbtack to drop from the metal rod is recorded in Table 3.
80
(a) Based on the results in Table 3,arrange the sequence of the heat conductivity of metal rod
K,L and M in descending order.
L,K and M
(b) State the variables in this experiment.
i. Constant : Diameter of metal rod
ii. Manipulated : Type of metal rod
iii. Respond : Time taken the thumbtack to fall
(c) What the hypothesis can be made from this experiment?
The type of metal rod used will effect the time taken of thumbtack to fall.
(d) If the metal rod used in this experiment are copper,iron and aluminium,identitiy metal rods
K,L and M that represent them.
K : Aluminium
L : Copper
M : Iron
SECTION B
4. Table 4 shows the melting point,boiling point and electrical conductivity of three types
of substance K,L and M.
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(a) i. Which substance possesses properties of ionic substance?
M
ii. Give a reason for your answer in 4(a)(i).
Substance M does not conduct electricity in the solid state but does so in the liquid
state.
(b) i. Which substance is a molecular substance?
K
ii. Give a reason for your answer in 4 (b)(i).
Its melting point and boiling point are very low.
(c) Why is it that substance M cannot conduct electricity in a solid state?
Iron does not move freely to carry electrical charges.
(d) Why is it that substance L can conduct electricity in both solid and liquid states?
There are electrons that move freely in substance L.
(e) Why does substance K have very low melting and boiling points?
Particles in substance K are held together by weak forces of attraction between the
particles.
5. Diagram 5 shows the structure of an atom of the helium element.
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(a) What are the proton number and nucleon number of helium?
Proton : 2
Nucleon : 4
(b) Complete Table 5 to differentiate between proton,neutron and electron.
Subatomic particle
Proton
Neutron
Electron
Relative charge
+1
0
-1
Relative mass
1
1
1/1840
(c) Name the group in which helium is located in the Periodic Table.
Group 18,unreactive (noble gas)
(d) What is the special characteristic of helium?
- Chemically stable
- Unreactive
6. Table 6 shows the proton number,number of electrons,nucleon number and number of
neutrons of atoms P,Q,R and S.
Particle
P
Q
R
S
Proton Number
3
4
6
6
Number of electrons
4
3
6
6
Nucleon number
7
9
12
13
atom Q and S.
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Number of neutrons
4
5
6
7
(a) Complete
Table 6 by
writing down
the number of
neutrons for
(b) i. Which of these particles is a positive ion?
Q
ii. Give a reason for your answer in 6 (b)(i).
The number of protons in particle Q is more than its number of electrons.
(c) i. Determine one particle which is a neutral atom.
R/S
ii. Give a reason for your answer in 6 (c)(i).
Its number of protons is the same as its number of electrons.
(d) i. Which of the particles are isotopes of the same element?
R and S
ii. Give a reason for your answer in 6 (d)(i).
R and S have the same number of protons but different number of neutrons.
7. Diagram 7 shows a part of the Periodic Table.
(a) How are the elements arranged in the Periodic Table?
In order of increasing proton number.
(b) Determine the element that is
i. the most reactive : R
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ii. not reactive : Q
(c) What is the proton number of elelment P?
Proton : 9
(d) Element P has a nucleon number orf 19.How many neutrons are there in element P?
Neutrons : 10
(e) Among these elements,which is
i. an atomic substance : R,S
ii. a molecular substance : P
(f) State two elements which will form an ionic substance when combined.
R and P or S and P.
(g) Which element has the most protons?
S
SECTION C
8. Study the following statement.
There is a difference in the melting points of atomic and
molecular substances
(a) Suggest one hypothesis to investigate the above statement.
Melting points of atomic substances are high while that of molecular substances are
low.
(b) i. Aim : To study the melting points of atomic and molecular substances
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ii. Variable that :
- Constant : Quantity of substances
- Manipulated : Type of substances
- Respond : Melting point of substance
iii. List of apparatus and materials : Lead filings,sulphur powder,crucible,clay triangle.
iv. Procedure :
- Two spatulas of lead filings are put into a crucible
- The crucible with its content is heated strongly.
- Observation about the melting point of lead filings is recorded.
- The experiment is repeated using the sulphur powder.
v. Tabulation of data :
Substance
Lead filings
Sulphur powder
Melting point/ °C
vi. Conclusion : An atomic substance has a high melting point while a molecular
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substances has a low melting point.
9. (a) Hypothesis : Metals conduct electricity while non-metal do not
i. Aim : To study the electrical conductivity of metals and non-metals
ii. Variable that :
- Constant : Size of the rod
- Manipulated : Copper rod and glass rod
- Respond : Electrical conductivity
iii. Materials and apparatus : Copper rod,glass rod,dry cell,bulb,connecting wire
iv. Procedure :
- A dry cell is connected to a bulb using a wire
- A copper rod is then connected to the electric circuit
- Observe whether the bulb lights up
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- The experiment is repeated using glass rod
v. Tabulation of data :
Type of rod
Copper rod
Glass rod
Condition of the bulb
10. (a) Four differences between ionic substance and molecular substance
Ionic substance
Solid at room temperature
Conduct electricity in molten form
Forces of attraction are very strong
High melting and boiling points
Molecular substance
Liquid at room temperature
Does not conduct electricity
Forces of attraction are weak
Low melting and boiling points
(b) i. Problem statement : Sodium chloride solution
ii. Name of the method : Crystallisation
iii. Step that must be taken :
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- Heat the sodium chloride solution to obtain the saturated solution
- Cool the saturated solution
- Sodium chloride crystals are obtained
11. (a) Four differences between metals and non-metals.
Metal
Has shiny surfaces
Ductile
High melting and boiling points
Good conductor of electricity
Good conductor of heat
Non-metal
Has dull surfaces
Not ductile
Low melting and boiling points
Poor conductor of electricity
Poor conductor of heat
(b) i. Identify the information
Butter and candle change into liquid state when they are heated
ii. Identify the common characteristic
- Heat is absorbed
- Substances melt
iii. Initial concept : Heat is absorbed by the substance causes the melting process
to occur.
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iv. Example : Ice cube
Non-example : Dry ice
v. Actual concept : Melting is a process of change in the state of matter when the
substance absorbs heat.
CHAPTER 5 : Energy and Chemical Changes
SECTION A
1. Diagram 1 shows the arrangement of apparatus used to determine the reactivity of metals
with
oxygen
Metal
Aluminium
Znc
Copper
Reactivity of metal with oxygen
Aluminium lights up brightly
Zinc glows with a bright flame
The copper glows dimly
The results of the experiment are shown in Table 1.
90
(a) Complete Table 1.
(b) Write one inference based on the observation in the experiment.
Aluminium is more reactive than copper
(c) State the variables in this experiment.
i. Constant : Quantity of metal
ii. Manipulated : Type of metal
iii. Respond : Reactivity of metal
(d) What is the function of potassium manganate(VII) crystals?
Supplying oxygen to react with metal.
(e) What is the function of the glass wool in this experiment?
Prevent the potassium from mixing with metal filings when heated.
(f) Why do metal filings need to be heated first before the heating of potassium manganate
(VII) crystals?
Metal filings can be react easily with oxygen.
(g) Based on your observation,arrange the reactivity of the three metals in decreasing order.
Aluminium,Zinc and Copper.
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2. Diagram 2 shows the arrangement of apparatus to study the purification of metal.
The experiment is repeated a few times with different quantities of electric current.The cathode is cleaned,dried
and weighed after 10 minutes for each experiment.The results obtained are recorded in Table 2.
Electriccurrent/C
Mass of cathode/g
300
1.05
600
1.10
900 1200
1.15 1.20
1500
1.25
1800
1.30
2100
1.35
(a) In Diagram 2,mark the positive electrode(anode) with the symbols ‘+’.
(b) Draw a graph showing the quantity of electric current versus the mass of cathode.
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(c) From the graph drawn,determine the mass of the cathode when the quantity of electric
current is 1200C.
1.20g
(d) Based on the graph in 2(b),what is the relationship between the quantity of electric current
and the mass of cathode?
The larger the quantity of electric current that flows,the higher the mass of cathode.
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3. Diagram 3 shows an experiment that is conducted to study the reaction between zinc and
hydrochloric acid.
The volume of hydrogen gas that is released is recorded every 30 seconds.The results obtained are recorded in
Table 3.
Time/second
Volume of hydrogen gas/cm³
0
0
30
25
60
38
90
46
120
50
(a) Based on Table 3,draw a graph of the volume of hydrogen gas against time.
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150
50
180
50
(b) Based on the graph drawn in 3(a),state the relationship between the volume of gas and time
in the first 90 seconds.
When the time increases,the volume of gas released also increases.
(c) State the variables in the experiment.
i. Manipulated : Time taken
ii. Respond : Volume of hydrogen gas
iii. Constant : Volume and concentration of acid
(d) Predict the volume of hydrogen gas that is collected at 210th second.
50cm³
(e) Give one other metal that can be used to replace zinc in this experiment.
Magnesium
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4. Diagram 4 shows an experiment carried out the study the heat change in chemical
reactions at room temperature (28.0 ºC)
(a) Based on Diagram 4,complete the Table 4.
Type of chemical substances
Potassium nitrate crystal
Sodium hydroxide crystal
Initial temperature (ºC)
28.0
28.0
Final temperature (ºC)
22.0
46.0
(b) State the variables in this experiment.
i. Manipulated : Type of chemical substances
ii. Respond : The final temperature
iii. Constant : Volume of distilled water
(c) What is the hypothesis that can be made for this experiment?
Different type of chemical reactions causes different changes in temperature.
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SECTION B
5. Diagram 5 shows the arrangement of apparatus for the electroplating of an iron nail with copper plate.
(a) Name the process occurred.
Electrolysis
(b) What the material is used as :
i. anode : Copper Plate
ii. cathode : Iron nail
(c) Suggest one electrolyte that can be used to replace copper(II) sulphate solution.
Copper (II) nitrate solution.
(d) State what can be observed of the following materials at the end of the experiment.
i. Copper plate : becomes thinner
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ii. Iron nail : is coated with a brown copper layer
(e) Write the energy transformation that occurs in this process.
Electrical energy
Chemical energy
(f) State two other uses of the process mentioned in 5 (a).
- Extraction
- Purification
6. Diagram 6 shows a model of a simple voltaic cell.
(a) What can be observed on the voltmeter?
The deflected galvanometer needle.
(b) Give an inference to the observation in 6(a).
Electrical energy is produced.
(c) Write the energy transformation that occurs in this experiment.
Chemical energy
Electrical energy
(d) i. What will happen if the copper plate is replaced with a carbon card?
The needle is deflected.
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ii. Give a reason for your answer in 6(d)(i).
The carbon is conducts electricity
(e) State one example of a food item which can be used to replace vinegar solution.
Orange
7. Diagram 7 shows the experiment to study the reaction of sodium with water.
(a) What happens to the sodium?
Sodium moves randomly on the surface of water and gives out a hissing sound.
(b) Name the gas released when sodium reacts with water.
Hydrogen
(c) i. What can be observed if a few drops of phenolphthalein indicator are dripped into
the basin?
Pink solution formed.
ii. Give the property of the solution formed.
Alkaline.
(d) Write one chemical equation in words for the reaction that occurs between sodium and
water.
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Sodium + water
Sodium hydroxide + hydrogen
8. Diagram 8 shows a piece of photographic paper.The centre section is covered with a
round piece of black paper and exposed to sunlight for one minute.
(a) Draw your observation at the end of the experiment.
(b) What is the layer that covers the photographic paper?
Silver chloride
(c) What happens to the layer you mentioned in 8(b) when it is exposed to sunlight?
Decomposed by light energy to silver atoms of a dark grey colour.
(d) Write an equation in words to explain the occurrence in 8(c).
Silver chloride
Silver + Chlorine
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SECTION C
9. Study the following statement.
Electrical energy can be produced from fruit
(a) Suggest one hypothesis to investigate the above statement.
Hypothesis : Electrical energy can be produced from fruit.
(b) i. Aim : To study the production of electrical energy from fruits.
ii. Variable that
- Constant : Type of metallic electrode
- Manipulated : Type of fruit
- Respond : Production of electrical energy
iii. List of apparatus and materials : Pineapple,orange,mango,iron plate,zinc plate,
connecting wire,crocodile clips,galvanometer
iv Procedure :
- The iron plate and zinc plate are connected with connecting wire and crocodile
clips to the galvanometer
- Both metallic plates are put into a pineapple.
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- Observation of the deflection of the galvanometer needle is recorded.
- The experiment is repeated using an orange and a mango.
v. Tabulation of data :
Fruit
Pineapple
Orange
Mango
Deflection of the galvanometer needle
vi. Conclusion : Electrical energy is produced when two different conductors are
dipped into an electrolyte solution.
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10. (a) State one method that can be used to plate the iron chain with the copper.
Electrolysis
- Copper plate is used as anode.
- Iron chain is used as cathode.
- Copper(II) chloride solution is used as electrolyte solution.
- Switch is turned on.
(b) i. Identify the problem : Extraction of tin form its ore
ii. Explain the problem : Tin needs to be separated from oxygen.
iii. Explain the method of extraction :
- Method 1 : Heat the tin ore with carbon
- Method 2 : Molten tin ore is electrolysed using carbon electrode.
iv. Choose the best method and explain your choice :
Method 1 is more suitable because it is cheaper.
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11. (a) Diagram 11.1 shows the addition of potassium iodine solution to the lead(II) nitrate
solution.
State four reasons why the above reaction is considered to be a chemical change.
i. New substances are formed.
ii. It involves a big chance in energy.
iii. The chemical properties and composition of the new substance are different from
those of the original.
iv. It is not a reversible change.
(b) Diagram 11.2 shows the physical changes in different substances.
104
i. - The shapes of the substances are changed.
- No new substance is formed.
ii. Initial concept : The shape of the substance changes but no new substance is formed
showing a physical change.
iii. Example : Ice melting
Non-example : Iron rusting
iv. Actual report : Physical change is a process that involves the change in the shape but
does not form a new substance.
CHAPTER 6 : Nuclear Energy
SECTION B
1. Diagram 1 shows the deflection of radioactive radiation.
105
(a) What are radiation X,Y and Z?
X : Alpha
Y : Gamma
Z : Beta
(b) Why does ray Y not deflect?
Ray Y not deflected because its neutral in terms of electrical charges.
(c) i. Which ray can be blocked by only a sheet of paper?
Ray X
ii. Give an inference for your answer in 1(c)(i).
Ray X because the penetrating power is low.
(d) What is the best way to store radioactive substances?
Store in thick lead containers surrounded by thick concretes.
(e) i. Which ray is the most dangerous?
Ray Y.
ii. Explain your answer in 1 (e)(i).
Ray Y because the penetrating power is high.
2. Diagram 2 shows the generation of electrical energy from a nuclear reactor.
106
(a) What processes take place at stages A,B and C?
A : Nuclear energy is produced by nuclear fission of uranium in a nuclear reactor.
B : Nuclear energy is converted to heat energy and boils water to produce steam.
C : Steam under high pressure rotates the turbine and generates electricity in the
generator.
(b) State the energy transformation that takes place during generation of electrical energy.
Nuclear energy
heat energy
kinetic energy
electrical energy
(c) Give two effects if nuclear energy is misused.
Explosion and pollution occur.
3. Diagram 3 shows the use of a radioactive substance in detecting a leak in an underground
water pipe.
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(a) State briefly how the work in Diagram 3 can be done?
- A small quantity of radioactive substance is put into water,gas/oil in an underground
pipe.
- The movement of the radioactive substance can be traced by using the Geiger-Muller
Counter.
(b) State two other uses of radioactive substances.
i. Medicine : kill cancer cell
ii. Food preservation : sterilising food
(c) Name one material which can be used to stop beta radiation.
Thin aluminium plate
(d) State two adverse effects of radioactive rays to human beings.
- Mutation
- Cancer
SECTION C
4. (a) State four differences between alpha and beta rays.
Alpha rays
Beta rays
108
Nucleus of helium
Positive charge
Low penetrating power
Can be blocked by a sheet of paper
High speed electrons
Negative charge
High penetrating power
Can be blocked by a thin sheet of aluminium
(b) i. Problem statement :
- Protecting from radioactive rays
- Storing radioactive substance in proper way
ii. Safety measures :
- Wearing a special protective outfit
- Wearing a film badge
iii. Method of storage :
- Store in thick lead containers
- Surrounded by a thick concrete
5. (a) Compare isotopes and radioisotopes by using examples of carbon-12 and carbon-14.
Similarity : Both have the same number of proton
Number of electrons
Number nucleon
Carbon-12 Isotopes
6
12
109
Carbon-14 Radioisotopes
8
14
Emits radioactive radiation
No
Yes
(b) Study the information and build a concept of beta rays.
i. Identify the information :
- Beta rays deflect to positive plate
- Beta rays can penetrate through a paper but cannot penetrate through a thin
aluminium sheet.
ii. Explain the information :
- Beta rays are negatively charged
- The penetrating power of beta rays is moderately high
iii. Initial concept : Beta rays are negatively charged and have a high penetrating
power
iv. Example : Can penetrate through thin plastic
Non-example : Cannot penetrate through thin plastic
v. Actual concept : Beta rays are rays with negative charge and have a moderately
high penetrating power.
CHAPTER 7: Light, Colour and Sight
SECTION A
1. Diagram 1.1 shows a part of the light rays on a plane mirror.
110
(a) Complete Diagram 1.1 by drawing the light rays reaching the observer’s eye.
(b) What is the relationship between distances X and Y?
X and Y are same distance
(c) State two characteristics of the image formed.
Virtual and upright
(d) In Diagram 1.2,draw the image formed on the plane mirror.Then,state the characteristic
of that image.
Characteristic of image : Inversed laterally
2. Diagram 2.1 shows an object placed in front of a pinhole camera.
111
(a) In Diagram 2.1,draw a ray diagram to show the image formed on the screen.
(b) State two characteristics of the image formed.
Real and inverted
(c) What is the effect to the image if
i. The size of the pinhole is enlarged?
More bright but blur.
ii. A convex lens is placed between the object and the pinhole?
The image will be more sharper.
iii. The pinhole camera is moved towards the object?
The image will be more bigger.
(d) Two more pinholes are punched in the camera as shown in Diagram 2.2.Draw and
label the image formed.
3. Diagram 3 shows a 0.7cm high object placed in front of a convex lens.
(a) Complete the ray diagram to show the formation of an image in Diagram 3.
112
(b) What is the height of the image formed?
0.7 cm
(c) State two characteristics of the image formed.
Real and inverted.
(d) What optical instrument possesses the object distance of 2F?
Photocopy machine
(e) Why can’t the location of the image be determined if the object is less than the
focal length of the lens,F?
The image is virtual.
4. Diagram 4 shows an experiment carried out to determine the focal length of
different convex lens.
113
(a) Measure the focal length of the convex lenses in Diagram 4 and write down their
focal length in Table 4.
Thickness of the convex lens
Thin
Thick
Focal length (cm)
3.6 ± (0.1)
2.4 ± (0.1)
(b) What is the inference that can be made for this experiment?
The thicker the thickness of the convex lens,the shorter the focal length.
(c) State the variables involved in this experiment.
i. Manipulated : The thickness of convex lens
ii. Respond : The focal length
iii. Constant : Light ray from distant object
(d) State the hypothesis for this experiment.
When the thickness of convex lens increases,The focal length will be decreases.
5. Diagram 5.1 and Diagram 5.2 show the experiment that is carried out to study the
image formed by a pinhole camera.
114
(a) Draw the light rays in Diagram 5.1 and Diagram 5.2 to show the formation of image.
(b) Measure the size of the image formed in Diagram 5.1 and Diagram 5.2.
i. Size of image in Diagram 5.1 : 0.4 ± (0.1 cm)
ii. Size of image in Diagram 5.2 : 0.5 ± (0.1 cm)
(c) State the variables involved in this experiment.
i. Manipulated : Distant of object
ii. Respond : Size of image formed
iii. Constant : Size of the object
(d) What is the hypothesis that can be made in this experiment?
When the distance of the object from the pinhole camera decreases,the size of image
will increases.
(e) State two characteristics of the image formed in this experiment.
Real and inverted.
(f) Predict the size of the image formed if the object is placed 15 cm from the pinhole.
Less than 0.4 cm
SECTION B
6. Diagram 6.1 shows the arrangement of apparatus used to study light dispersion.
115
(a) i. What happens to the white lights at the border of the prism?
Refracted
ii. Give a reason for your answer in 6(a)(i)
It is because the white light are refracted from one medium to another with
different densities or angles.
(b) What is the colour of the light formed at P and Q on the white cardboard?
P : Red
Q : Violet
(c) Complete the boxes below to show the sequence of colours formed in the spectrum.
P(Red),Orange,Yellow,Green,Blue,Indigo,Q(Violet).
(d) A similar prism is palced in the position as shown in Diagram 6.2.
ii.
What can be observed on the white cardboard?
White light.
ii. State one natural phenomena in which a spectrum can be seen.
116
Formation of rainbow.
7. Diagram 7 shows the structure of a camera.
117
(a) Label structure X and Y.
X : Diaphragm
Y : Film
(b) Name the structures of the human eye which are analogous to structures X and Y.
X : Iris
Y : Retina
(c) What is the function of X in the camera?
Controls the size of aperture and amount of light that enters to the camera.
(d) How can a sharp image be focused in a camera?
The lens focuses the image of an object onto the film.The lens is adjusted by the
focus adjuster either towards or away from the film to obtain a sharp image.
8. Diagram 8 shows the formation of a rainbow after an evening rain.
118
(a) How is a rainbow formed?
- Sunlight shines on the raindrop.
- A part of the light is reflected off the outer surface of the raindrop.
- A part of the light is refracted at the different angles in the raindrop.
- The light is split into its colour constituents through dispersion.
- The colour constituents are reflacted off the far inner surface of the raindrop.
- Light refraction occurs again as it exits the raindrop.A rainbow is formed.
(b) What is the role of the raindrops?
Act as a prism.
(c) State two processes that occurred to the sunlight at X?
Dispersion and refracted.
(d) What process occurs to the sunlight at Y?
Reflected
9. Diagram 9 shows the arrangement of apparatus to study the addition of coloured light.
119
(a) What colours are formed in the regions of X,Y and Z?
X : Red
Y : Magenta
Z : Blue
(b) i. Of the colours formed on the screen,which is the secondary colour?
Magenta.
ii. Give a reason for your answer in 9(b)(i).
Magenta can only be produced from addition of two primary colours,blue and red.
(c) What coloured light is formed in region X if a yellow filter is placed in front of the
red filter in torch P?
Red.
(d) What coloured light is formed in region Z if a green filter is placed in front of the
blue filter in torch Q?
No colour formed.
(e) If a piece of cyan cloth is placed under the light rays in region Y,what colour will the
cloth appear as?
Blue.
SECTION C
20. Study the following statement.
120
The spectacles of old people have shorter focal length than those of a student who is
long-sighted.This is because the lenses in their spectacles have a different thickness.
(a) Suggest one hypothesis to investigate the above statement.
Hypothesis : The thicker a lens,the shorter its focal length.
(b) i. Aim : To estimate the focal length of a convex lens and relate it to the thickness of
the lens.
ii. Variable that :
- Constant : Object distance
- Manipulated : Thickness of the lens
- Respond : Focal length
iii. List of apparatus and materials : Metre ruler,screen,convex lenses with vary
thickness,lens holder.
iv. Procedure :
- The arrangement of apparatus is set up as shown in the diagram below,facing an
object outside the window.
- The screen is adjusted until a sharp image is formed on it.
121
- The focal length is measured with a metre ruler.
- The experiment is repeated using lenses of different thickness.
v. Tabulation of data :
Thickness of the lens
Thin
Thick
Focal length, f/cm
vi Conclusion : A thick convex lens has a short focal length while a thin convex lens has
a long focal length.
11. (a) Contrast the mechanism of focusing and the mechanism of controlling the amount
of light entering the human eye and the camera.
Mechanism of focusing :
- Eye : Focussing is done when thickness of the lens is regulated by the ciliary
body.
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- Camera : Focussing is done by regulating the distance between the lens and
the film.
Mechanism of controlling the amount of light :
- Eye : The amount of light entering the eyes is controlled by the iris.
- Camera : The amount of light entering the camera is controlled by the
diaphragm.
(b) Explain how the student can build one device to solve his problem.
i. Problem statement : Seeing an object behind the wall.
ii. Name of the device : Periscope
iii. Name of the light principle that applied : Reflection
iv. Step in building the device :
- Two plane mirrors are arranged parallel to one another at an angle of
45º.
- Light rays from the first mirror are incident to the surface of the second
mirror.
- The second mirror reflects the light rays to the eyes of the student.
12. (a) Compare the images formed by a concave lens and a magnifying glass.
- The images formed by a concave lens and a magnifying glass are virtual
and upright.
- A magnifying glass forms a bigger image than the object.
(b) Diagram 12 shows the colours that appear in the screen when white light is passed
123
through the coloured filters.
i. Identify the problem :
- A red filter only allows green light to pass through it.
- A green filter only allows green light to pass through it.
ii. Identify two common characteristics :
- Red and green coloured filters only allow their own colours to pass
through them.
- Other colours are absorbed by red and green coloured filters.
iii. Initial concept :
Red and green coloured filters only allow their own colours to pass through
them but absorb other colours showing that they are primary colours.
iv. Example : Blue
Non-example : Yellow,cyan,magenta
v. Actual concept :
Primary filters only allow their own colours to pass through them but absorbed
other colours.
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CHAPTER 8 : Chemicals in Industry
SECTION A
3. Diagram 1 shows that a steel ball is attached to the surface of a pure copper block with cellophane tape.
A weight is dropped on atop of the copper block from a height of 50 cm. The diameter of dent formed is
recorded. The experiment is repeated with a bronze block. Table 1 shows the result of the experiment.
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Ex periment
Diameter of dent on pure copper block/mm
Diameter of dent on bronze block/mm
Average diameter of dent/mm
4.2
3.8
Table 1
(f) Based on the results on the experiment, which block is harder?
Bronze block.
(g) What is relationship between the diameter of dent formed and the hardness of metal or alloy?
The smaller the diameter of the dent formed, the harder is the metalor alloy.
(h) What hypothesis can be made from this experiment?
The diameter of a dent formed on the pure copper block is bigger.
(i) State the variable that
(iv)
Is kept constant
Height of the weight.
(v)
Is manipulated
Type of block
(vi)
Respond
Diameter of dent.
(j) Define alloy operationally based on the results of the experiment.
Alloy is a material in which the depression produced on it is smaller.
4. Diagram 2 shows the experiment to study the rusting of metals.
Both test tubes with their contents are left for three days. The results are recorded in Table 2.
Type of nails
Iron nail
Stainless steel nail
Observations
Rust
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Table 2
(e) Complete Table 2 by showing what has happened to the stainless steel nail at the end of the
experiment.
Does not rust.
(f) Which nail is more resistant to corronsion?
Stainless steel nail.
(g) State the variable
( i ) is kept constant : Volume and concentration of sodium chloride solution.
( ii) is manipulated : Type of nail.
( iii) responds :Rusting of the nail.
(h) Define alloy operationally based on the observation of the experiment.
Alloy is a material which does not rust.
SECTION B
3. Brass and steel are two examples of alloy.Brass which consists of copper and another
element is harder than pure copper.
(a) What element is mixed with copper to form brass?
Zinc.
(b) What type of particles is found in pure copper?
Atom.
(c) Draw and label the arrangement of particles in pure copper and in brass.
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(d) Explain why brass is harder than pure copper.
The atoms in pure copper are the same in size and are packed closely.Layers of these
atoms easily slide over one another when force is applied.The zinc and copper atoms
in brass are of different sizes.This disrupts the arrangement of the layers of atoms
and make them difficult to slide over one another.
(e) State the pure metal and foreign atoms that form steel.
Pure metal : Iron
Foreign atom : Carbon
4. Diagram 4 shows the disposal of industrial waste from a chemical factory that
manufactures chemicals needed for the growth of crops.
(a) State one product that could be produced by the factory.
Fertiliser.
(b) State two pollutants that might be disposed from the factory into the river.
128
Nitrate and phosphate compounds
(c) State one adverse effects of the pollutants in 4(b) on the environment.
Disrupt the balance of aquatic ecosystem.
(d) The factory uses petroleum as the source energy.
i. State one acidic gas produced in the burning of fossil fuel.
Sulphur dioxide
ii. State one method to control air pollutant in 4(d)(i) from the factory.
Dissolve the gas using air cleaner system before release to air.
5. Air pollution is caused by the burning of fossil fuel from factories.
(a) Give three examples of pollutants which may be contained in the smoke released
from factory chimneys.
Carbon monoxide,dust and sulphur dioxide.
(b) i. What happens if acidic gas dissolves in rain water?
Acid rain.
ii. State one effect of pollution to the environment and human health caused by the
event in 5(b)(i).
Environment : Lower pH value
Human health : Respiratory system
(c) Suggest one way how factories can reduce the release of acidic gas into the air.
129
Dissolve the gas using air cleaner system before release to air.
(d) Apart from factories,what other source that causes poisonous gases to be releases to the
surroundings?
Motor vehicles
SECTION C
6. Study the following statement.
Iron nails left outside the house rust
compared to stainless steel nail.
easily
(a) Suggest one hypothesis to investigate the above statement.
Hypothesis : A stainless steel nail does not rust easily compared to an iron nail.
(b) i. Aim : To study the resistance of stainless steel nail to rusting.
ii. Variable that :
- Constant : Concentration and volume of sodium chloride solution.
- Manipulated : Type of nail
- Respond : Rusting of nail
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iii. List of apparatus and materials : 0.5 mol dm‾³ sodium chloride solution,iron nail,
stainless steel nail,test tubes,test tube rack.
iv. Procedure :
- Test tubes A and B are each filled with 5 cm³ of sodium chloride solution.
- An iron nail is put into test tubes A and stainless steel nail into test tube B.
- Both test tubes are left on a rack for three days.
- Observation of the nails is recorded.
v. Tabulation of data :
Type of nail
Iron nail
Stainless steel nail
xiv.
Observation
Conclusion : Alloy is more resistant to rust than pure metal.
131
7. (a) State one process that can be used to produce this chemical substance.Explain.
- Haber process
- One volume of nitrogen and three volumes of hydrogen are used.
- Temperatures between 450-500 °C and 200-500 atmosphere pressure.
- Iron filings are used as the catalyst.
(b) Explain how he can prepare ammonia fertilizer by using the following substances.
i. Ammonium sulphate
ii. Crystallisation
iii. - Excess ammonia solution is added to sulphuric acid.
- The mixture is heated until saturated.
- The solution is left to cool.
- Ammonium sulphate crystals are produced.
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8. (a) State four differences between bronze and copper.
Bronze
Mixture of copper and tin
Harder
Stronger
Can withstand corrosion
Copper
Consists of copper only
Softer
Less strong
Cannot withstand corrosion
(b) i. Identify the common characteristics :
- Contain two or more metals
- Stronger than pure metals
ii. Initial concept : Substance that contains two or more metals and is stronger
compared to pure metals is an alloy.
iii. Example : Bronze
Non-example : Tin
iv. Actual concept : Alloy is a substance that contains two or more metals and is
more stronger compared to pure metals.
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