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ISC Class 12 Chemistry Solved Question Paper 2004

Short Answer Type

11.

Correct the following statements:
Ethyl acetate undergoes saponification on treatment with dilute hydrochloric acid.

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12.

Correct the following statements:
Aromatic compounds undergo nucleophilic substitution reaction.

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13.

Correct the following statements:
Isotopes have the same mass number and atomic number.

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14. Why does soda water fizz when the bottle is opened ? Name the law that explains this phenomenon.

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15. Explain nuclear fission with one example. Mention any two applications of nuclear fission.

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16. An aqueous solution containing 0.2 g of compound A in 21.7 g of water freezes at 272.814 K. If the value of K_ffor water is 1.86 K kg mol^{– 1}, calculate molecular weight of compound A.

We have, K_f = 1.86 K kg mol^{– 1}
w = 0.2 g,
W = 21.7 g,
ΔT_f= 272.814 K.

Now comma Molecular space weight space left parenthesis straight m right parenthesis space equals space fraction numerator 1000 space straight x space straight K subscript straight f space straight x space straight w over denominator increment straight T subscript straight f space straight x space straight W end fraction space Putting space the space value space in space the space equation space equals space fraction numerator 1000 straight x space 1.86 space straight x space 0.2 over denominator 272.814 space straight x space 21.7 end fraction space equals space 0.063 space gm

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17. Draw the electron dot or equivalent structure of HClO₄ and name the types of bonds present.

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18. Explain the purification of common salt by bubbling hydrogen chloride gas through its solution.

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19. The initial rate of a reaction A + B → products is doubled when the initial concentration of A is doubled and increases eight fold when the initial concentration of both A and B were doubled. State the order of the reaction with respect to A and with respect to B. Write the rate equation.

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20. A gas cylinder of 5 litre capacity containing 4 kg of helium gas at 27°C developed a leak leading to the escape of gas into the atmosphere. If the atmospheric pressure was 1.0 atmosphere, calculate the work done by the gas, assuming ideal behaviour.

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