CBSE SCIENCE SAMPLE PAPER 2011 SOLUTION
Solutions:
1]
Gallium or Cesium (any one).
2]
Cerebellum
3]
Since ventricles have to pump blood into various organs, therefore, they have thicker
muscular walls than the auricles.
4]
Commercial unit of energy is Kilowatt hour or KWh.
5]
Chemical reaction in which one reactant gets oxidized while the other gets reduced is
called a redox reaction.
Mg gets oxidized on burning in air.
6]
(i) Fresh milk is acidic and gets spoiled easily. In presence of baking soda, milk
becomes alkaline and can be stored for a longer time.
(ii) When milk sets to curd, pH decreases. The alkali does not allow it to become
more acidic easily. So it takes more time.
7]
Name of gland Secretion
Salivary gland Saliva
Gastric gland Gastric juice
Liver Bile
Pancreas Pancreatic Juice
(any two)
8]
(a) When Iron nails are kept into a copper sulphate solution, Iron displaces copper
from CuSO4 solution and blue colour of CuSO4 solution becomes light green.
(b)
9]
(a) Ionic compounds are formed by the transfer of electrons from metal to non
metal.
(b)
10
] (a) Respiration is an exothermic process since energy is released during the
process.
(b) Energy in the form of heat, light or electricity is required for decomposition
Reactions hence these are endothermic.
(c)
The solution becomes colourless because of copper sulphate formed which is
colourless.
11
]
(i) Test the three solutions with blue litmus paper, the one solution will change blue
litmus into red it is Acidic solution
(ii) Test the remaining two solution with the red litmus (Changed in activity (i)) one
solution will change it again to blue It is basic solution. (iii) Remaining third solutions
is distilled water
12
]
13
]
In series (i) R1 = 5+5 =10
(ii) R2 = 6+4 = 10
In pararell
(i)
14]
(i) Glottis gets covered by a small cartilaginous flap of skin called epiglottis which
prevents the entry of food particles into wind pipe while swallowing.
(ii) The lung alveoli are richly supplied with blood capillaries for the exchange of
gases. From the thin walls of alveoli, oxygen diffuses into blood and is supplied to
the tissues while carbon dioxide is absorbed by blood from the tissues and is carried
to the alveoli of lungs for exhalation.
(iii) The walls of trachea is supported by C – shaped cartilage rings which does allow
the trachea to collapse in the presence of less air in it.
15]
Hind brain has three parts:
(i) Cerebellum: It is the regulating centre for swallowing, coughing, sneezing and
vomiting and helps to maintain the balance of the body and coordinate the muscular
activities.
(ii) Pons: It takes part in the regulation of respiration.
(iii) Medulla oblongata: It is responsible for the coordination and adjustment of
movement and posture.
16]
(a) Diagram of Neuron:
Functions of Neuron:
(i) To carry information from receptors to brain and spinal cord.
(ii) To transfer respose from brain and spinal cord to effectors.
17]
(a) Auxin.
When light is coming from one side of the plant auxin diffuses towards shady sides.
This concentration stimulates the cells to grow longer on the side of the shoot which
is away from the light and shoot bends.
18]
(i) Magnetic field will increase
(ii) Magnetic field will decrease
(iii) Magnetic field will increase
19]
(i) Wave energy be a viable proposition only when waves are very strong. [1x3=3]
(ii) A tidal power station at the mouth of a river blocks the flow of polluted water into
the sea. It creates health and pollution hazards.
(iii) Efficient commercial exploitation is difficult or any other.
20]
(a)
(b) Functions of two chambers of human heart:
Left Atrium – Receive oxygenated blood from pulmonary vein
Right Atrium – Receive deoxygenated blood from vena cava
Left Ventricle – Pumps oxygenated blood to all parts of body
Right Ventricle – Pumps deoxygenated blood to lungs. (Any two)
OR
(a) Diagram of stomata:
(b) Functions of stomata:
(a) Exchange of gases
(b) Transpiration
Raw materials for photosynthesis CO2, H2O
21]
(a) The chemical name of washing soda is Sodium carbonate Decahydrate.
The formula is Na2CO3.10H2O
It is obtained by heating baking Soda and then recrystallization.
(b) Distilled water is a pure form of water and is devoid of any ionic species.
Therefore, it does not conduct electricity. Rain water, being an impure form of water,
contains many ionic species such as acids and therefore it conducts electricity.
OR
(a)
(i) Neutral- Solution D with pH 7 (ii) Strongly alkaline- Solution C with pH 11 (iii)
Strongly acidic- Solution B with pH 1 (iv) Weakly acidic- Solution A with pH 4 (v)
Weakly alkaline- Solution E with pH 9
The pH can be arranged in the increasing order of the concentration of hydrogen
ions as: 11 < 9 < 7 < 4 < 1
(b) The fizzing will occur strongly in test tube A, in which hydrochloric acid (HCl) is
added.
This is because HCl is a stronger acid than CH3COOH and therefore produces
hydrogen gas at a faster speed due to which fizzing occurs.
22]
(i) Metal – sodium
(ii)
(iii)Electrolysis of molten chloride (NaCl) is the process.
i.e. we can write:
OR
Definition: Homogeneous mixture of two or more metals or a metal and a non metal
is called an alloy.
Prepared: (i) By melting the primary metal.
(ii) By dissolving the other elements in a definite proportion and cooled to room
temperature.
23]
A coil of many circular turns of insulated copper wire wrapped closely in the shape of
a cylinder.
The magnetic field is uniform inside the solenoid
Used to magnetise a piece of magnetic material.
OR
(a)
(i) Right hand Thumb rule
(ii) Fleming's Left hand rule
(iii) Fleming's Right hand rule
(b)
(a) To avoid the risk of electric shocks
(b)To save the electrical appliances from damage.
24]
(a)
(i) Momentary deflection in the galvanometer to one side.
(ii) Momentary deflection in the galvanometer now in opposite direction.
(iii) No deflection in the galvanometer. Phenomenon involved is electromagnetic
induction.
(b) An energy source that can be replenished in a short period of time and state one
use each.
Eg. Solar Energy, Wind energy, Ocean energy etc. Any use.
OR
(a)Argon or Neon gas is filled in the electric bulbs.
These are used since these are inactive or inert gases to prolong life of the
filament. (b)
(i) Length of the conductor: proportional
(ii) Area of cross section: inversely proportional
(iii) Material of conductor
25]
26]
II
27]
1A in Circuit I and 0A in Circuit II
28]
9
29]
Parallel in circuit I and in series in circuit II
30]
A=Digestor,B=Gas outlet
31]
Safrainin
32]
Alcohol
33]
Alcohol is inflammable
34]
Germinating seeds
35]
To absorb CO2 released by germinating seeds
36]
Covered portion of any of the above
37]
Green
38]
Sodium bicarbonate > Water > Fruit juice
39]
A
40]
Light green
41]
NaOH
42]
(i) and (ii)