JEE Main > Chemical Kinetics

Explore popular questions from Chemical Kinetics for JEE Main. This collection covers Chemical Kinetics previous year JEE Main questions hand picked by popular teachers.


Q 1.    

Correct4

Incorrect-1

Units of rate constant of first and zero order reactions in terms of molarity {tex}\mathrm{M}{/tex} unit are respectively

{tex} \sec ^ { - 1 } , \operatorname { Msec } ^ { - 1 } {/tex}

B

{tex} \sec ^ { - 1 } , \mathrm { M } {/tex}

C

{tex} \mathrm { Msec } ^ { - 1 } , \mathrm { sec } ^ { - 1 } {/tex}

D

{tex} \mathrm { M } , \mathrm { sec } ^ { - 1 } {/tex}

Explanation


Q 2.    

Correct4

Incorrect-1

For the reaction {tex} A + 2 B \rightarrow C , {/tex} rate is given by {tex} R = [ A ] [ B ] ^ { 2 } {/tex} then the order of the reaction is

3

B

6

C

5

D

7

Explanation


Q 3.    

Correct4

Incorrect-1

The differential rate law for the reaction {tex} H_{2}+I_{2} \rightarrow 2HI{/tex} is

A

{tex} - \frac { d \left[ \mathrm { H } _ { 2 } \right] } { d t } = - \frac { d \left[ \mathrm { I } _ { 2 } \right] } { d t } = - \frac { d [ \mathrm { HI } ] } { d t } {/tex}

B

{tex} \frac { d \left[ \mathrm { H } _ { 2 } \right] } { d t } = \frac { d \left[ \mathrm { I } _ { 2 } \right] } { d t } = \frac { 1 } { 2 } \frac { d [ \mathrm { HI } ] } { d t } {/tex}

C

{tex} \frac { 1 } { 2 } \frac { d \left[ \mathrm { H } _ { 2 } \right] } { d t } = \frac { 1 } { 2 } \frac { d \left[ \mathrm { I } _ { 2 } \right] } { d t } = - \frac { d [ \mathrm { HI } ] } { d t } {/tex}

{tex} - 2 \frac { d \left[ \mathrm { H } _ { 2 } \right] } { d t } = - 2 \frac { d \left[ \mathrm { I } _ { 2 } \right] } { d t } = \frac { d [ \mathrm { HI } ] } { d t } {/tex}

Explanation


Q 4.    

Correct4

Incorrect-1

The formation of gas at the surface of tungsten due to adsorption is the reaction of order

0

B

1

C

2

D

insufficient data.

Explanation

Q 5.    

Correct4

Incorrect-1

The rate law for a reaction between the substances {tex} A {/tex} and {tex} B {/tex} is given by rate {tex} = k [ A ] ^ { n } [ B ] ^ { m } {/tex}. On doubling the concentration of {tex} A {/tex} and halving the concentration of {tex} B , {/tex} the ratio of the new rate to the earlier rate of the reaction will be as

A

{tex} \frac { 1 } { 2 ^ { m + n } } {/tex}

B

{tex} ( m + n ) {/tex}

C

{tex} ( n - m ) {/tex}

{tex} 2^{( n - m )} {/tex}

Explanation


Q 6.    

Correct4

Incorrect-1

For the reaction system: {tex}{ 2 \mathrm { NO } _ { ( \mathrm { g } ) } + \mathrm { O } _ { 2 ( \mathrm { g } ) } \rightarrow 2 \mathrm { NO } _ { 2 ( \mathrm { g } ) }}{/tex} volume is suddenly reduced to half its value by increasing the pressure on it. If the reaction is of first order with respect to {tex} \mathrm { O } _ { 2 } {/tex} and second order with respect to {tex}\mathrm { NO } _ { 2 }{/tex} the rate of reaction will

A

diminish to one-fourth of its initial value

B

diminish to one-eighth of its initial value

increase to eight times of its initial value

D

increase to four times of its initial value.

Explanation


Q 7.    

Correct4

Incorrect-1

In the respect of the equation {tex} k = A e ^ { - E _ { a } / R T } {/tex} in chemical kinetics, which one of the following statements is is correct?

A

{tex} k {/tex} is equilibrium constant

B

{tex} A {/tex} is adsorption factor

{tex} E _ { a } {/tex} is energy of activation

D

{tex} R {/tex} is Rydberg constant.

Explanation


Q 8.    

Correct4

Incorrect-1

In a first order reaction, the concentration of the reactant, decreases from {tex} 0.8 \mathrm { M } {/tex} to {tex} 0.4 \mathrm { M } {/tex} in {tex}15{/tex} minutes. The time taken for the concentration to change from {tex} 0.1 \mathrm { M } {/tex} to {tex} 0.025 \mathrm { M } {/tex} is

30 minutes

B

15 minutes

C

7.5 minutes

D

60 minutes

Explanation


Q 9.    

Correct4

Incorrect-1

The rate equation for the reaction {tex} 2 A + B \rightarrow C {/tex} is found to be : rate {tex} = k [ A ] [ B ] {/tex}. The correct statement in relation to this reaction is that the

A

unit of {tex} k {/tex} must be {tex} \mathrm { s } ^ { - 1 } {/tex}

B

{tex} t _ { 1 / 2 } {/tex} is a constant

C

rate of formation of {tex} C {/tex} is twice the rate of disappearance of {tex} A {/tex}

value of {tex} k {/tex} is independent of the initial concentrations of {tex} A {/tex} and {tex} B . {/tex}

Explanation


Q 10.    

Correct4

Incorrect-1

A reaction involving two different reactants can never be

unimolecular reaction

B

first order reaction

C

second order reaction

D

bimolecular reaction

Explanation



Q 11.    

Correct4

Incorrect-1

{tex} t _ { 1/4 } {/tex} can be taken as the time taken for the concentration of a reactant to drop to {tex} 3 / 4 {/tex} of its initial value. If the rate constant for a first order reaction is {tex} k , {/tex} the {tex} t _ { 1/4 } {/tex} can be written as

A

{tex} 0.10 / k {/tex}

{tex} 0.29 / k {/tex}

C

{tex} 0.69 / k {/tex}

D

{tex} 0.75 / k {/tex}

Explanation

Q 12.    

Correct4

Incorrect-1

A reaction was found to be second order with respect to the concentration of carbon monoxide. If the concentration of carbon monoxide is doubled, with everything else kept the same, the rate of reaction will be

A

remain unchanged

B

tripled

increased by a factor of {tex}4{/tex}

D

doubled

Explanation


Q 13.    

Correct4

Incorrect-1

Rate of a reaction can be expressed by Arrhenius equation as : {tex} k = A e ^ { - E/ R T } . {/tex} In this equation, {tex} E {/tex} represents

A

the energy above which all the colliding molecules will react

the energy below which colliding molecules will not react

C

the total energy of the reacting molecules at a temperature, {tex} T {/tex}

D

the fraction of molecules with energy greater than the activation energy of the reaction.

Explanation


Q 14.    

Correct4

Incorrect-1

The following mechanism has been proposed for the reaction of {tex}\mathrm N\mathrm O {/tex} with {tex}\mathrm B\mathrm r_{2}{/tex} to {tex}\mathrm N\mathrm O\mathrm B\mathrm r. {/tex} {tex}\mathrm N\mathrm O_{(g)} +\mathrm B\mathrm r_{2(g)}\rightleftharpoons\mathrm N\mathrm O\mathrm B\mathrm r_{2(g)}{/tex}
{tex}\mathrm N\mathrm O\mathrm B\mathrm r_{2(g)}+\mathrm N\mathrm O_{(g)}\rightarrow 2 N\mathrm O\mathrm B\mathrm r_{(g)}{/tex}

A

1

B

0

C

3

2

Explanation


Q 15.    

Correct4

Incorrect-1

The energies of activation fro forward and reverse reactions for {tex}A_2+B_2\rightleftharpoons2AB{/tex} are {tex}180 \mathrm kJ \mathrm mol^{-1}{/tex}and {tex}200 \mathrm kJ \mathrm mol^{-1}{/tex} respectively.The presence of a catalyst lowers the activiation energy of both(forward and reverse)reactions by {tex}100 \mathrm kJ \mathrm mol^{-1}.{/tex}The enthalpy change of reaction {tex}(A_2+B_2\rightarrow2AB){/tex} in the presence of a catalyst will be {tex}(\mathrm in \ \mathrm kJ \mathrm mol^{-1}){/tex}

20

B

300

C

120

D

280

Explanation



Q 16.    

Correct4

Incorrect-1

Consider the reaction, {tex} 2 A + B \rightarrow {/tex} products. When concentration of {tex} B {/tex} alone was doubled, the half-life did not change. When the concentration of {tex} A {/tex} alone was doubled, the rate increased by two times. The unit of rate constant for this reaction is

A

{tex} s ^ { - 1 } {/tex}

{tex} \mathrm { L } \mathrm { mol } ^ { - 1 } \mathrm { s } ^ { - 1 } {/tex}

C

no unit

D

{tex} \operatorname { mol } \mathrm { L } ^ { - 1 } \mathrm { s } ^ { - 1 } {/tex}

Explanation


Q 17.    

Correct4

Incorrect-1

For a reaction {tex} \frac { 1 } { 2 } A \rightarrow 2 B {/tex} rate of disappearance of {tex} A {/tex} is related to the rate of appearance of {tex} B {/tex} by the expression

A

{tex} - \frac { d [ A ] } { d t } = 4 \frac { d [ B ] } { d t } {/tex}

B

{tex} - \frac { d [ A ] } { d t } = \frac { 1 } { 2 } \frac { d [ B ] } { d t } {/tex}

{tex} - \frac { d [ A ] } { d t } = \frac { 1 } { 4 } \frac { d [ B ] } { d t } {/tex}

D

{tex} - \frac { d [ A ] } { d t } = \frac { d [ B ] } { d t } {/tex}

Explanation


Q 18.    

Correct4

Incorrect-1

A substance having initial concentration{tex}\mathrm{'a'\ mole/L}{/tex} reacts according to zero order reaction. The time taken for completion of reaction is

A

{tex} \frac { 2 \mathrm { a } } { \mathrm { k } } {/tex}

{tex} \frac { \mathrm { a } } { \mathrm { k } } {/tex}

C

{tex} \frac { \mathrm a } { 2 \mathrm k } {/tex}

D

{tex} \frac {\mathrm k } { \mathrm a } {/tex}

Explanation

Q 19.    

Correct4

Incorrect-1

Rate constant of a first order reaction is {tex} 6.93 \times 10 ^ { - 3 } \mathrm { min } ^ { - 1 } {/tex}. If we start with {tex} 10 \mathrm { mol/L } {/tex}. It is reduced to {tex} 1.25 \mathrm { mol/L } {/tex} in

A

{tex}\mathrm{100\ minute}{/tex}

B

{tex}\mathrm{200\ minute}{/tex}

C

{tex}\mathrm{30\ minute}{/tex}

{tex}\mathrm{300\ minute}{/tex}

Explanation



Q 20.    

Correct4

Incorrect-1

The reaction {tex}\mathrm{ A + 2 B + C \rightarrow 2 D + E }{/tex} is found to be {tex} 1,2 {/tex} and zero order with respect to {tex} \mathrm{A , B} {/tex} and {tex} \mathrm C {/tex} respectively. What will be the final rate, if concentration of each reactant is doubled?

A

{tex}\mathrm{2\ times}{/tex}

B

{tex}\mathrm{4\ times}{/tex}

{tex}\mathrm{8\ times}{/tex}

D

{tex}\mathrm{16\ times}{/tex}

Explanation



Q 21.    

Correct4

Incorrect-1

For a reaction {tex} \mathrm { N } _ { 2 } \mathrm { O } _ { 5 } \longrightarrow 2 \mathrm { NO } _ { 2 } + \frac { 1 } { 2 } \mathrm { O } _ { 2 } {/tex}
Given: {tex} - \frac { \mathrm { d } \left( \mathrm { N } _ { 2 } \mathrm { O } _ { 5 } \right) } { \mathrm { dt } } = \mathrm { k } _ { 1 } \left[ \mathrm { N } _ { 2 } \mathrm { O } _ { 5 } \right] {/tex}, {tex} \frac { \mathrm { d } \left( \mathrm { NO } _ { 2 } \right) } { \mathrm { dt } } = \mathrm { k } _ { 2 } \left[ \mathrm { N } _ { 2 } \mathrm { O } _ { 5 } \right] {/tex}, {tex} \frac { \mathrm { d } \left( \mathrm { O } _ { 2 } \right) } { \mathrm { dt } } = \mathrm { k } _ { 3 } \left[ \mathrm { N } _ { 2 } \mathrm { O } _ { 5 } \right] {/tex}
The relation between {tex} \mathrm { k } _ { 1 } , \mathrm { k } _ { 2 } {/tex} and {tex} \mathrm { k } _ { 3 } {/tex} are

{tex} \mathrm{2 k _ { 1 } = k _ { 2 } = 4 k _ { 3 }} {/tex}

B

{tex}\mathrm{ k _ { 1 } = k _ { 2 } = k _ { 3 }} {/tex}

C

{tex}\mathrm{ 2 k _ { 1 } = 4 k _ { 2 } = k _ { 3 }} {/tex}

D

{tex} \mathrm{1 / 2 k _ { 1 } = k _ { 2 } = 1 / 4 k _ { 3 }} {/tex}

Explanation





Q 22.    

Correct4

Incorrect-1

The concentration of a reactant in a solution falls from {tex} 0.2 \mathrm { \ M } {/tex} to {tex} 0.1 \mathrm { \ M } {/tex} in {tex}2{/tex} hours and to {tex} 0.05 \mathrm { \ M } {/tex} in {tex}4{/tex} hours. The order of reaction is

A

Zero

B

Two

One

D

Half

Explanation

Q 23.    

Correct4

Incorrect-1

Which of the following is an incorrect statement?

A

Half life of second order reaction decreases with increase in concentration of reactant

B

Half life of first order is independent of concentration of the reactant

C

The unit of rate constant of zero order is equal to unit of rate

The unit of frequency factor 'A' in Arrhenius equation is the unit of half life of the reaction

Explanation



Q 24.    

Correct4

Incorrect-1

For a hypothetical reaction {tex} x + y = A + B , {/tex} Rate {tex} = k [ x ] ^ { 5 / 2 } [ y ] ^ { - 1 / 2 } {/tex} on doubling the concentration of {tex} x {/tex} and {tex} y {/tex} the rate will become

A

2 times

4 times

C

8 times

D

Remains same

Explanation



Q 25.    

Correct4

Incorrect-1

The gaseous reaction {tex} A ( g ) \rightarrow 2 B ( g ) + C ( g ) {/tex} obeys first order kinetics. If the initial {tex} P = 90 \mathrm { mm } {/tex} and pressure after {tex}10{/tex} minutes {tex} = 180 \mathrm { mm } {/tex}. The velocity constant {tex} k {/tex} of the reaction is

A

{tex} 1.15 \times 10 ^ { + 3 } \mathrm { s } ^ { - 1 } {/tex}

B

{tex} 2.30 \times 10 ^ { + 3 } \mathrm { s } ^ { - 1 } {/tex}

C

{tex} 3.45 \times 10 ^ { - 3 } \mathrm { s } ^ { - 1 } {/tex}

{tex} 1.15 \times 10 ^ { - 3 } \mathrm { s } ^ { - 1 } {/tex}

Explanation