: CBSE Sample Question Papers

Foreign

Section - A

1. Give an example of a reaction catalysed by an enzyme.
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2. Name the groups of compounds with the following functional groups :
(i) -COOH
(ii)- NH₂
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3. Name two main combustible components of Biogas.
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4. Why are some stars red and some blue in colour ?
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5. In what situation do we use Fleming’s right-hand rule ?
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6. What change is made in the hardness of steel when :
(i) it is quenched, and
(ii) it is annealed ?
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7. What is meant by decarboxylation and esterification of acetic acid ?

OR
Name the products obtained and the chemical equations for oxidation of ethanol to different stages.
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8. What is the technique employed to obtain information about the internal layer structure of earth Name the layers of earth other than its crust.
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9. What characteristics should be possessed by the fuel to be used in space rockets ? Give an example ot such fuels.
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10. With the help of a diagram show how the fission reaction of ²³⁵U with thermal neutrons develops into a chain reaction.
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11. What is meant by the pH of a solution ? What pH values can be expected for 1 M HCI and solutions and a solution made by mixing equal volumes of the two solutions
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12. How is vulcanised rubber obtained from natural rubber ? What structural change is involved in this process ? Give an example of synthetic rubbers. To which class of polymers does this rubber belong .

OR
What are detergents chemically ? What is their advantage over soaps for washing clothes ? How does a soap solution wash out dirt from clothes ?
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13. State reasons for the following : .
(i) Zinc oxide is called an amphoteric oxide. (ii) Sodium metal is stored in bottles filled with kerosene oil. (iii) Eatables can be preserved in nitrogen gas.
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14. Write chemical equations for the reactions taking place when :
(i) a piece of zinc is placed in a solution of copper (II) sulphate. (ii) sulphur dioxide gas is dissolved in an excess of NaOH solution. (iii) a mixture of ammonia and oxygen gases is passed over platinum heated to about 1073 K-
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15. (a) Two conductors A and B of resistances 5 ohm and 10 ohm respectively can be arranged in Parailel and later on in series. In each arrangement the total voltage applied across it is 20 volts. I’1 wmcl1 arrangement will the voltage across A and B be the same and in which case will the current flowing through A and B be the same ?
(b) Calculate the total resistance for each arrangement.
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All India

Section - A

1. How is the rate of reaction influenced by
(i) raising the temperature of reactants ?
(ii) adding to the reacting mixture a product of reaction without change in volume ? 1
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2. How are the molecules of aldehydes and ketones structurally different ? 1
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3. Name one non-metal and one metal which are in liquid state at room temperature. 1
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4. Name two other planets of the Solar System which are similar to the Earth in composition and structure.1
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5. How is the strength of the magnetic field at a point near a wire related to the strength of the electric current flowing in the wire ? 1
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6. How is chloride of lime chemically different from calcium chloride ? Why does chloride of lime gradually lose its chlorine when kept exposed to air ? 2
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7. What is formalin ? How does it react with Tollen’s reagent ? State any one of its uses.

OR
Complete the following reaction equations :

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8. What is a galaxy ? Name two common shapes of galaxies. Why is our galaxy called Milky War ? 2
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9. State one point of difference between a natural satellite and an artificial satellite. Name the type of orbit suitable for a geostationary satellite. 2
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10. Give one example of a nuclear fusion reaction. Describe one method for making such reactions possible. 2
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11. State Arrhenius’ concept of acids and bases. Giving reason, select a strong acid and a weak base from amongst the following substances :
H₂CO₃, HNO₃, NaOH, NH₄OH 3
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12. How is it that we can use detergents for washing clothes even when the water is hard, but not soaps ? What change has been made in the composition of detergents to make them biodegradable ?

OR
What is a polymer ? How have been polymers been classified ? Name one polymer for each of the following applications : (i) For insulating electric wires. (ii) For non-stick coatings on kitchen utensils. (iii) For blending with cotton to make shrink-resist cloth. 3
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13. Give reasons for the following :
(i) Silicon counts among metalloids.
(ii) Carbon is not used for making aluminium from aluminium oxide.
(iii) For making hydrogen by reaction with hydrochloric acid, granulated zinc is preferred to a block of zinc. 3
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14. Write chemical equations for reactions taking place when :
(i) Zinc carbonate is calcined.
(ii) Ammonia gas is passed over heated copper (II) oxide. (iii) SO₂ gas and H₂S gas are together bubbled through water. 3
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15. What are electrolytes ? Define Faraday’s constant for electrolytic reactions. Find chemical equivalents of Cu(II) (at. wt. 63.5) and Ag(I) (at. wt. 108). 3
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Delhi

Section - A

1. Draw a figure to show how the rate of a chemical reaction in general changes as the temperature of reactants is increased step-wise. 1
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2. Name the classes of organic compounds represented by the following formulae :

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3. Name any two neutral oxides. 1
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4. What type of force or forces keep the Sun and its planets in their respective places ?

OR
What force makes an apple on a tree to fall to the ground and what force makes a balloon filled with
hydrogen to rise into air ? 1
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5. How can it be shown that a magnetic field exists around a wire through which a direct electric current is passing ? 1
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6. What is the chemical name of washing soda ? Name the three chief raw materials used for making washing soda by the Solvay process. 2
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7. What is meant by ‘fermentation’ ? Write chemical equations for the two steps involved in preparing ethanol by the fermentation of molasses.

OR
Name the main products formed when :
(i) Ethanol is oxidised by an alkaline solution of KMnO₄.
(ii) Propanone and hydrogen cyanide form an addition compound.
(iii) Sodium ethanoate is heated with soda lime.
(iv) Methanal is reduced with hydrogen in the presence of finely divided palladium. 2
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8. To which galaxy does our earth belong ? How is the shape of this galaxy described ?
‘Our universe is expanding’. What does it mean ? 2
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9. In cases of artificial satellites what are ‘equatorial’ and ‘polar’ orbits ? Which type of these satellite orbitals will be suitable for collecting data for weather prediction and why ? 2
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10. Which type of nuclear process is currently used in nuclear electricity generators ? Give one example each for the substances used in this context as :
(i) coolants, (ii) moderators, and (iii) nuclear fuel. 2
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11. When will the reversible reaction,
N₂(g) + O₂(g)=2NO(g)
be said to be in equilibrium state ? Write the formula co-relating the concentration of involved substances in this equilibrium state. A reversible reaction has a very low value of its equilibrium constant. What does it signify for the rate of progress of the reaction ? 3
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12. Besides being large molecules what is the other essential similar structural character of all polymers ? Give one example each for the formation of (0 an addition polymer and (if) a condensation polymer.

OR
State the monomers used and one use each for :
(a) Neoprene, (b) Teflon and © Natural rubber. 3
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13. (a) What are strategic metals ? Give one example also.
(b) State the reason for the following behaviour of zinc metal :
On placing a piece of zinc metal in a solution of mercuric chloride it acquires a shining silvery surface but when it is placed in a solution of magnesium sulphate no change is observed. 3
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14. Write chemical equations for the reactions taking place when :
(i) A piece of calcium metal is placed in water. (ii) Ammonia gas comes in contact with hydrogen chloride gas. (iii) Sulphur is heated with concentrated H₂SO₄. 3
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15. State the formula correlating the electric current flowing in a conductor and the voltage applied across it. Also show this relationship by drawing a diagram. What would be resistance of a conductor if the current flowing through it is 0.35 ampere when the Xpotential difference across it 1.4 volt ? 3
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