Chemical Kinetics MCQs and Answers

1 For a first order reaction A → B the rate constant is x min−1 . If the initial concentration of A is 0.01M , the concentration of A after one hour is given by the expression.

2 A zero order reaction X →Product , with an initial concentration 0.02M has a half life of 10 min. if one starts with concentration 0.04M, then the half life is

3 For a first order reaction A → product with initial concentration x mol L−1 , has a half life period of 2.5 hours . For the same reaction with initial concentration (x/2) mol L−1 the half life is

4 For the reaction, 2NH3 → N2 + 3H2

then the relation between k1, k2 and k3 is

5 The decomposition of phosphine (PH3) on tungsten at low pressure is a first order reaction. It is because the

6 For a reaction Rate = k[acetone]3/2 acetone then unit of rate constant and rate of reaction respectively is

7 The addition of a catalyst during a chemical reaction alters which of the following quantities?

8

Consider the following statements :

(i) increase in concentration of the reactant increases the rate of a zero order reaction.

(ii) rate constant k is equal to collision frequency A if E_a = 0

(iii) rate constant k is equal to collision frequency A if E_a = °

(iv) a plot of ln(k) vs T is a straight line

(v) a plot of ln (k) vs 1/T  is a straight line with a positive slope.

 

Correct statements are

9

In a reversible reaction, the enthalpy change and the activation energy in the forward direction are respectively −x kJ mol⁻¹ and y kJ mol⁻¹ . Therefore , the energy of activation in the backward direction is

a) b) c) d)

10

What is the activation energy for a reaction if its rate doubles when the temperature is raised from 200K to 400K? (R = 8.314 JK^-1mol^-1)