12/18/2011 CBSE


Q. 1. Biological reactions in our body depend on the presence of
biocatalysts. What name is given to these catalysts? How is their activity
influenced by changes in temperature? 1

Q. 2. Name two metals both of which are very ductile as well as
very malleable. 1

Q. 3. Write the chemical equation to represent the reaction taking
place when copper oxide is heated in a stream of hydrogen.

Q. 4. What are the values of (z) the angle of incidence, and (if)
the angle of reflection for normal incidence on a plane mirror surface?

Q. 5. A wire of resistance 10 ohm is bent in the form of a closed
circle. What is the effective resistance between the two points at the ends of
any diameter of the circle? 1

Q. 6. What happens when crystals of washing soda are left open in
dry air? What is this change named as? Name two industries based on use of
washing soda. 2

Q. 7. "Sulphuric acid is a dibasic acid." Write two reaction
equations to justify this statement and name the reaction products in the two
cases. 2

Q. 8. Explain the principle involved in the launching of
artificial satellites. 2

Q. 9. Light enters from air into a glass plate which has a
refractive index of 1.50. Calculate the speed of light in glass. The speed of
light in air is 3.0 x 108 mar -1. 2

Q. 10. Distinguish between 'prompt', 'delayed' and 'spontaneous'
fissions of nuclei. 2
Define a 'nuclear fusion
reaction'. Describe the conditions for the occurrence of a nuclear fusion

Q. 11. When does a reversible chemical reaction reach a state of
equilibrium? Write the expression for the equilibrium constant (K) for the
equilibrium reaction.
H2(g) + I2(g) ----> 2 HI(g)
How will
the numerical value of equilibrium constant (K) change if the equation of the
equilibrium reaction is written as:
H2(g) + I2(g) ----> 2 HI(g)
Q. 12. Describe the 'steam reforming process' of manufacture
of hydrogen from natural gas with the help of necessary chemical equations.

Q. 13. Give the name and formula of the monomer of natural rubber.
Why is natural rubber vulcanised? Write two uses of vulcanized rubber.

Q. 14. (a) Write the chemical equation representing the
preparation reaction of ethanol from ethene.

(b) Name the product obtained when ethanol is oxidised by either
chromic anhydride or alkaline potassium permanganate,

(c) Give an example of an esterification reaction.
Differentiate between a soap and a detergent on the
basis of their chemical constitutions. For cleansing action when is a detergent
preferred to a soap?

Q. 15. If a 12 V battery is connected to the arrangement of
resistances given below, calculate
(i) the total effective resistance of the
arrangement and
(ii) the total current flowing in the circuit.

Q. 16. What is meant by the 'calorific value' of a fuel? How is it
determined? Arrange the following fuels in a decreasing order of their calorific
Kerosene, Coal, LPG 3

Q. 17. Write three major activities of the Indian Space Research
Organisation (ISRO). 3

Q. 18. Name an important oxide ore of iron. Describe the
extraction of iron from this ore under the following heads:
(ii) Reduction of the concentrated ore
(iii) Diagram
of the furnace used
(iv) Chemical equations for the reactions
(a) What is an 'activity series' of metals? Arrange the
metals Zn, Mg, Al, Cu and Fe in a decreasing order of reactivity.
(b) What
would you observe when you put
(i) Some zinc pieces into blue copper sulphate
(ii) Some copper pieces into green ferrous sulphate
(c) Name a metal which combines with hydrogen gas. Name the
compound formed.

Q. 19. What is long-sightedness? List two causes for development
of long-sightedness. Describe with a ray diagram, how this defect may be
corrected by using spectacles. 5
What is an
astronomical telescope? Draw a labelled ray diagram showing the formation of
image of a distant object by an astronomical telescope. State the magnification
produced by a telescope in normal adjustment. How can the magnification power of
a telescope be increased?

Q. 20. State 'Fleming's right-hand rule'. With a labelled diagram,
describe the working of an AC electric generator. 5


Q. 21. Write the full form of IUCD. 1

Q. 22. What is the function of genes in an organism?

Q. 23. Why is it necessary to conserve our environment?

Q. 24. Define the term 'pollution'. Describe UASB method of
checking water pollution. 2
Q. 25. How are the following
caused and what is the effect of each of them on our environment?
(i) Depletion of ozone layer (ii) Acid rain
is meant by soil erosion? Describe two practices by which soil erosion can be

Q. 26. Name the constituents of blood. Why are white blood
corpuscles called 'soldiers of the body'? 3
Draw a
diagram of human heart and label the following on it:
(i) Aorta
Pulmonary trunk
(iii) Superior vena cava
(iv) Coronary arteries.

Q. 27. Draw a diagram of the nervous system in an insect. Label
the following parts on it: 3
(i) Brain (ii) Ganglion (iii)
Nerve cord.

Q. 28. Explain the terms, 'fission' and 'regeneration' as used in
relation to reproduction. 3

Q. 29. Explain the mechanism of sex determination in the zygote.

Q. 30. Define the terms 'nutrition' and 'nutrients'. List two
differences between 'Holozoic nutrition' and 'Saprophytic nutrition'. Give two
examples of each of these two types of nutrition.

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