To crack difficult exams like JEE and NEET and also to perform good in boards, a lot of practice is required. Here you have some questions on the topic chemical kinetics.

## Practice questions on chemical kinetics

#### 1

In reaction 2H_{2}O_{2} → 2H_{2}O + O_{2}, rate of formation of O2 is 2.6 mol/L×sec then rate of disappearance of H_{2}O_{2} is-

- 2.6 mol/l×sec
- 1.3 mol/l×sec
- 5.2 mol/l×sec
- 4.6 mol/l×sec

Correct answer : 3

#### 2

For reaction A → A_{(g)} + ½ C _{(g)} at t=0 total pressure is 8atm, at time t=10sec total pressure of reaction is 10atm.calculate the rate of reactant A in atm×sec^{-1} is ?

- 0.2
- 0.4
- 1.0
- 1.8

#### 3

For reaction A + B → product, concentration of A and B with rate of reaction changes as follow

A B ROR

1. 0.02 0.08 1×10^-2

2. 0.04 0.08 2×10^-2

3. 0.02 0.16 4×10^-2 Order of reaction is-

- 3
- 2
- 1
- 4

Correct answer : 1

#### 4

Activation energy of a chemical reaction can be determined by

- Determining the rate constant at standard temperature
- Evaluating the rate constants at two different temperatures
- Determining probability of collision
- Evaluating velocity of reaction at two different temperature

Correct answer : 2

#### 5

A reaction follows zero order reaction. concentration of reactant is change as follow

In every 3 minute

20 →15 → X → Y , value of X and Y is (time interval is same 3 minute)-

- 7.5 & 3.75
- 10 & 5
- 7.5 & 5
- 10 & 3.75

Correct answer : 2

#### 6

For a first order reaction A→B, the reaction rate at reactant concentration of 0.01 M is found to be 2.0×10^{−5} molL^{−1} s^{−1} . The half-life period of the reaction is:

- 220 sec
- 30 sec
- 300 sec
- 347 sec

Correct answer : 4

#### 7

In zero order reaction slop of t_{1/2} v/s a is (a is initial contraction of reactant)-

- 1/2K
- 2k
- 1/K
- K

Correct answer : 1

#### 8

A substance ‘A’ decompose by a first order reaction starting initially with [A] = 2.00M and after 200min, [A] becomes 0.15M. For this reaction t_{1/2} is

- 53.72 min
- 50.49 min
- 48.45 min
- 46.45 min

Correct answer : 1

#### 9

Which is not correct for catalytic affect on reaction?

- Catalyst does not change the equilibrium constant of reaction
- Catalyst increases Gibbs Energy
- It affect forward as well as backward at same extent
- It decreases activation energy of reaction

Correct answer : 2. Gibbs Energy does not alter.

#### 10

Units of rate constant of first and zero order reactions in terms of molarity M units are respectively.

- sec
^{-1}, Msec^{-1} - sec
^{-1}, M - Msec
^{-1}, sec^{-1} - M, sec
^{-1}

Correct answer : 1

#### 11

A reaction follow zero order, slop of graph between t_{1/2} and concentration of reactant is 45°. Calculate the rate constant for reaction.

- 0.5 mol/lit×sec
- 2.0 mol/lit×sec
- 1.414 mol/lit×sec
- 1.0 mol/lit×sec

Correct answer : 1

#### 12

For a first order reaction half life is 30 minute. The value of t_{99%} is ?

- 100 minutes
- 200 minutes
- 150 minutes
- 250 minutes

Correct answer : 2

#### 13

Which of the following is not correct(first order reaction) ?

- t
_{75%}= 2 × t_{50%} - t
_{87.5%}= 3 × t_{50%} - t90% = 3.33 × t
_{50%} - t
_{99%}= 4 × t_{50%}

Correct answer : 4

#### 14

A first order reaction take 8 minutes to complete 90% reaction. Time taken in completing 99% is-

- 16 minutes
- 12 minutes
- 14 minutes
- 10 minutes

Correct answer : 1; t_{99%} = 2×t_{90%}

#### 15

The temperature dependence of rate constant (k) of a chemical reaction is written in terms of Arrhenius equation k=Ae^{−E/RT} . Activation energy (Ea) of the reaction can be calculated by plotting-

- K v/s T
- logk v/s 1/T
- K v/s 1/logT
- logK v/s 1/logT

Correct answer : 2

#### 16

A hypothetical reaction A2 + B2 → 2AB follow the following mechanism

A_{2} <^{__}>A + A (fast)

A + B_{2} → AB + B (slow)

A + B → AB (fast)

The order of the overall reaction is-

- 2
- 0
- 1
- 3/2

Correct answer : 4

#### 17

For a reaction value of rate constant k is 2.4 × 10^{-6} mole/lit×sec. The reaction is-

- Zero order
- First order
- Second order
- None

Correct answer : 1

#### 18

For A_{(g)} + B_{(g)} → C_{(g)} + D_{(g)}, If initial concentration of A and B are increased by factor 2 and 4 respectively and R = k [A][B]^{1/2}, then the initial rate is changed by factor

- 2
- 4
- 6
- Remain constant

Correct answer : 2

#### 19

First order reaction completes 75% in 100 minutes. How long will it take for 87.5% completion?

- 200 minutes
- 175 minutes
- 150 minutes
- 125 minutes

Correct answer : 3

#### 20

For an exothermic reaction :

- Ea > ΔH
- Ea < ΔH
- Ea = ΔH
- None of the above

Correct answer : 4