Chemistry 12 Chapter 4 Exemplar Solutions Chemical Kinetics Part 3

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Question 16:

A first order reaction is completed in s. How much time would it take for completion?

(i)

(ii)

(iii)

(iv) Infinite

Answer: (iv)

Question 17:

Compounds ‘A’ and ‘B’ react according to the following chemical equation.

Concentration of either ‘A’ or ‘B’ were changed keeping the concentrations of one of the reactants constant and rates were measured as a function of initial concentration. Following results were obtained. Choose the correct option for the rate equations for this reaction.

Experiment

Experiment

Initial concentration of

Initial concentration of

Initial concentration of

1.

2.

3.

0.30

0.30

0.60

0.30

0.60

0.30

0.10

0.40

0.20

(i)

(ii)

(iii)

(iv)

Answer: (ii)

Question 18:

Which of the following statement is not correct for the catalyst?

(i) It catalyses the forward and backward reaction to the same extent.

(ii) It alters ΔG of the reaction.

(iii) It is a substance that does not change the equilibrium constant of a reaction.

(iv) It provides an alternate mechanism by reducing activation energy between reactants and products.

Answer: (ii)

Question 19:

The value of rate constant of a pseudo first order reaction ____________.

(i) Depends on the concentration of reactants present in small amount.

(ii) Depends on the concentration of reactants present in excess.

(iii) Is independent of the concentration of reactants.

(iv) Depends only on temperature.

Answer: (ii)

Question 20:

Consider the reaction A B. The concentration of both the reactants and the products varies exponentially with time. Which of the following figures correctly describes the change in concentration of reactants and products with time?

(i)

Concentration of reactants

Concentration of Reactants

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(ii)

Concentration of reactants

Concentration of Reactants

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(iii)

Concentration of reactants

Concentration of Reactants

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(iv)

Concentration of reactants

Concentration of Reactants

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Answer: (ii)