Class 12 Chemistry Chapter 4 Chemical Kinetics Objective Type Questions and Answers | Class 12 Chemistry Chapter 4 Chemical Kinetics Quiz

1 The rate constant of a reaction depends upon

A temperature of the reaction

B extent of the reaction

C initial concentration of the reactants

D the time of completion of reaction

Answer:the time of completion of reaction

2 For a reaction nx – y → z the rate of reaction becomes twenty seven times when the concentration of X is increased three times. What is the order of the reaction?

A 2

B 1

C 0

D 3

View Answer

Answer:3

3 Fora reaction x + y → z, rate ∝ |X|. What is (i) moleculariiy and (ii) order of reaction?

A (i)2, (ii)1

B (i)2, (ii)2

C (i)1, (ii)1

D (i)1, (ii) 2

View Answer

Answer: (i)2, (ii)1

4 The unit of rate constant for the reaction
2H₂ + 2NO → 2H₂O + N₂
which has rate = K|H₂||NO|², is

A mol L^-1 s^-1

B s^-1

C mol^-2 L² s^-1

D mol L^-1

View Answer

Answer:mol^-2 L² s^-1

5 Which of the following, is an example of a fractional order reaction?

A NH₄NO₂ → N₂ + 2H₂O

B NO + O₃ → NO₂ + O₂

C 2NO + Br₂ → 2NOBr

D CH₃CHO → CH₄ + CO

View Answer

Answer: CH₃CHO → CH₄ + CO

6 A reaction in which reactants (R) are converted into products (P) follows second order kinetics. If concentration of R is increased by four times, what will be the increase in the rate of formation of P?

A 9 times

B 4 times

C 16 times

D 8 times

View Answer

Answer:16 times

7 The decomposition of dimethyl ether is a fractional order reaction. The rate is given by rate =k(PCH₃OCH₃)^3/2. If the pressure is measured in bar and time in minutes, then what are the units of rate and rate constant?

A bar min^-1, bar² min^-1

B bar min^-1, bar^1/2 min^-1

C bar^1/2 min^-1, bar² min^-1

D bar min^-1, bar^1/2 min^-1

View Answer

Answer:bar min^-1, bar^1/2 min^-1

8 In a reaction, 2X → Y, the concentration of X decreases from 0.50 M to 0.38 M in 10 min. What is the rate of reaction in Ms-1 during this interval ?

A 2 × 10-4

B 4 × 10-2

C 2 × 10-2

D 1 × 10-2

View Answer

Answer:2 × 10-4

9 If the rate of a reaction is expressed by, rate = A [A]² [B], the order of reaction will be

A 2

B 3

C 1

D 0

View Answer

Answer: 3

10 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.

A 0.01 e^−x

B 1 x10^-2 (1-e^-60x)

C (1x10^-2) e^-60x

D none of these

View Answer

Answer: (1x10^-2) e^-60x

11 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

A 10 s

B 5 min

C 20 min

D Cannot be predicted using the given information

View Answer

Answer: 20 min

12 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

A (2.5 × 2) hours

B (2.5 / 2) hours

C 2.5 hours

D Without knowing the rate constant, t_1/2 cannot be determined from the given data

View Answer

Answer: Without knowing the rate constant, t_1/2 cannot be determined from the given data

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

A rate is proportional to the surface coverage

B rate is inversely proportional to the surface coverage

C rate is independent of the surface coverage

D rate of decomposition is slow

View Answer

Answer: rate is independent of the surface coverage

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

A (mol L^-1s^-1), (mol^-1/2 L^1/2 s^-1)

B (mol^-1/2 L^1/2s^-1), (mol L^-1 s^-1)

C (mol^1/2 L^1/2s^-1), (mol L^-1 s^-1)

D (mol Ls^-1), (mol^1/2 L^1/2 s^-1)

View Answer

Answer:(mol^-1/2 L^1/2s^-1), (mol L^-1 s^-1)

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

A Enthalpy

B Activation energy

C Entropy

D Internal energy

View Answer

Answer:Activation energy

16 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 Ea = 0
(iii) rate constant k is equal to collision frequency A if Ea = °
(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

A (ii) only

B (ii) and (iv)

C (ii) and (v)

D (i), (ii) and (v)

View Answer

Answer: (ii) only

17 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 ( y −x ) kJ mol⁻¹

B ( x + y )J mol⁻¹

C ( x −y ) kJ mol⁻¹

D ( x + y ) × 103 J mol⁻¹

View Answer

Answer:( x + y ) × 103 J mol⁻¹

18 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)

A 234.65 kJ mol⁻¹K⁻¹

B 434.65 kJ mol⁻¹K⁻¹

C 334.65 J mol⁻¹K⁻¹

D 434.65 J mol⁻¹K⁻¹

View Answer

Answer: 434.65 J mol⁻¹K⁻¹

19 Assertion: rate of reaction doubles when the concentration of the reactant is doubles if it is a first order reaction.
Reason: rate constant also doubles

A Both assertion and reason are true and reason is the correct explanation of assertion

B Both assertion and reason are true but reason is not the correct explanation of assertion

C Assertion is true but reason is false

D Both assertion and reason are false

View Answer