Chemistry 12 Chapter 4 Exemplar Solutions Chemical Kinetics Part 1

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I. Multiple Choice Questions (Type-I)

Question 1:

The role of a catalyst is to change ______________.

(i) Gibbs energy of reaction.

(ii) Enthalpy of reaction.

(iii) Activation energy of reaction.

(iv) Equilibrium constant.

Answer: (iii)

Question 2:

In the presence of a catalyst, the heat evolved or absorbed during the reaction ___________.

(i) Increases.

(ii) Decreases.

(iii) Remains unchanged.

(iv) May increase or decrease.

Answer: (iii)

Question 3:

Activation energy of a chemical reaction can be determined by _____________.

(i) Determining the rate constant at standard temperature.

(ii) Determining the rate constants at two temperatures.

(iii) Determining probability of collision.

(iv) Using catalyst.

Answer: (ii)

Question 4:

Consider Fig. 4.1 and mark the correct option.

Reaction coordinate

Reaction Coordinate

Fig. 4.1

(i) Activation energy of forward reaction is and product is less stable than reactant.

(ii) Activation energy of forward reaction is and product is more stable than reactant.

(iii) Activation energy of both forward and backward reaction is and reactant is more stable than product.

(iv) Activation energy of backward reaction is and product is more stable than reactant.

Answer: (i)

Question 5:

Consider a first order gas phase decomposition reaction given below:

The initial pressure of the system before decomposition of A was . After lapse of time ‘’, total pressure of the system increased by x units and became ‘p_t The rate constant k for the reaction is given as _________.

(i)

(ii)

(iii)

(iv)

Answer: (ii)

Question 6:

According to Arrhenius equation rate constant is equal to . Which of the following options represents the graph of ?

(i)

Arrhenius equation rate

Arrhenius Equation Rate

(ii)

Represents the graph

Represents the Graph

(iii)

Represents the graph

Represents the Graph

(iv)

Represents the graph

Represents the Graph

Answer: (i)

Question 7:

Consider the Arrhenius equation given below and mark the correct option.

(i) Rate constant increases exponentially with increasing activation energy and decreasing temperature.

(ii) Rate constant decreases exponentially with increasing activation energy and decreasing temperature.

(iii) Rate constant increases exponentially with decreasing activation energy and decreasing temperature.

(iv) Rate constant increases exponentially with decreasing activation energy and increasing temperature.

Answer: (iv)

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