CBSE Chemistry Model Test Paper : Set II
1. What is efflorescence? Name one compound which shows efflorescence.
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2. Which process is used for the enrichment of
(a) sulphide ores, (b) oxide ores?
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3. Name two metals which are purified by liquation.
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4. A white coloured compound reacts vigorously with water. The solution formed turns red litmus blue. It is used in the blast furnace to remove the sand from the ore. Write the commercial name of the compound and its chemical formula. Write two other uses of this compound.
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5. Write two points of differences between roasting and calcination.
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6. (a) At 298 K, the equilibrium concentrations of the reactants and products for
the reaction, N2 (g) + 3H2 (g) = 2NH3(g) are as follows:
[N2] = 0.001 M; [H2] = 0.02 M and [NH3] = 0.5 M. Calculate the equilibrium constant at this temperature.
(b) If temperature is increased, what effect it will have on the value of the equilibrium constant of the above reaction? The formation of NH3 is an exothermic reaction.
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7. Explain the following terms:
(a) Esterification
(b) Saponification
© Decarboxylation.
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8. (a) What is Tollen’s reagent?
(b) Which class of compounds give Tollen’s test?
© Write the reactions involved in the Tollen’s test.
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9. (a) What are alloys? Why are alloys made?
(b) Name an alloy of
(i) aluminium used in the construction of aircrafts.
(ii) iron used for making surgical instruments.
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10. (a) Write one reaction in each case to illustrate the following: (i) reducing action of ammonia (ii) oxidising action of sulphur dioxide.
(b) In the Contact process for the manufacture of sulphuric acid (i) name the catalyst.
(ii) name the substance in which sulphur trioxide is dissolved. (iii) name the substance which is diluted with water.
© The crystal of the substance ‘X’ is blue in colour. When it is placed in conc.H2SO4, it becomes white. Identify ‘X’ and explain the observation.
(a) Liquid hydrogen is used as a rocket fuel. It is used in space shuttles.
(i) Another gas must be carried by a space shuttle in order to burn the hydrogen. What is the name of this gas? (ii) Suggest a reason why the space shuttle carries liquid hydrogen rather than hydrogen gas.
(b) (i) It has been suggested that hydrogen could be developed as an alternative fuel for the future.
Suggest one reason hydrogen has over fossil fuels.
(ii) Give one other industrial use of hydrogen.
© Write a chemical equation for the laboratory preparation of hydrogen gas.
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