Chemistry MCQs for Class 12 with Answers Chemical Kinetics

1

This reaction follows first order kinetics. The rate constant at particular temperature is 2.303 × 10−2 hour−1 . The initial concentration of cyclopropane is 0.25M. What will be the concentration of cyclopropane after 1806 minutes? (log 2 = 0.3010)

A 0.125M

B 0.215M

C 0.25 × 2.303M

D 0.05M

View Answer

Answer: 0.215M

2 For a first order reaction, the rate constant is 6.909 min-1.the time taken for 75% conversion in minutes is

A (3/2)log2

B (2/3)log2

C (3/2)log(3/4)

D (2/3)log(4/3)

View Answer

Answer: (2/3)log2

3 In a first order reaction x → y ; if k is the rate constant and the initial concentration of the reactant x is 0.1M, then, the half life is

MCQ on Chemical Kinectics

A (a)

B (b)

C (c)

D (d)

View Answer

Answer:(c)

4 Predict the rate law of the following reaction based on the data given below

2A + B → C + 3D

MCQ on Chemical Kinectics

A rate = k [ A]² [B]

B rate = k [ A][B]²

C rate = k [ A][B]

D rate = k [ A]^1/2 [B]^3/2

View Answer

Answer: rate = k [ A][B]²

5 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

Answer: Assertion is true but reason is false.

6 The rate constant of a reaction is 5.8 × 10⁻² s⁻¹ . The order of the reaction is

A First order

B zero order

C Second order

D Third order

View Answer

Answer: First order

7

For the reaction N₂O₅(g) → 2NO₂ (g) + ½ O₂(g), the value of rate of disappearance of N₂O₅ is given as 6.5 × 10^-2 mol L^-1 s^-1. The rate of formation of NO₂ and O₂ is given respectively as

A

( 3.25 × 10⁻² mol L⁻¹s⁻¹ ) and (1.3 × 10⁻² mol L⁻¹s⁻¹)

B

(1.3 × 10⁻² mol L⁻¹s⁻¹ ) and ( 3.25 × 10⁻² mol L⁻¹s⁻¹ )

C

(1.3 × 10⁻¹ mol L⁻¹s⁻¹ ) and ( 3.25 × 10⁻² mol L⁻¹s⁻¹ )

D None of these

View Answer

Answer:
(1.3 × 10⁻¹ mol L⁻¹s⁻¹ ) and ( 3.25 × 10⁻² mol L⁻¹s⁻¹ )

8 During the decomposition of H2O2 to give dioxygen, 48 g O2 is formed per minute at certain point of time. The rate of formation of water at this point is

A 0.75 mol min⁻¹

B 1.5 mol min⁻¹

C 2.25 mol min⁻¹

D 3.0 mol min⁻¹

View Answer

Answer: 3.0 mol min⁻¹

9 If the initial concentration of the reactant is doubled, the time for half reaction is also doubled. Then the order of the reaction is

A Zero

B one

C Fraction

D none

View Answer

Answer: Zero

10 In a homogeneous reaction A →B + C + D , the initial pressure was P0 and after time t it was P. expression for rate constant in terms of P0, P and t will be

Chemical Kinetics