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JEE • CHEMISTRY • CHEMICAL KINETICS

Chemical kinetics practice · Mixed difficulty

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These sets use single-correct-answer MCQs. They do not cover every JEE Main or JEE Advanced question format and are not full-length mock papers.

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Showing 1-30 of 301 questions

1 Hard

1 of 301

Analyzing +4 | -1

The reaction

\mathrm{A}_2+\mathrm{B}_2 \rightarrow 2 \mathrm{AB}

follows the mechanism

\begin{aligned} & {{\text{A}}_2}\mathop \rightleftharpoons \limits_{{{\text{k}}_{ - 1}}}^{{{\text{k}}_1}} {\text{A}} + {\text{A (fast) }} \\ & \mathrm{A}+\mathrm{B}_2 \xrightarrow{\mathrm{k}_2} \mathrm{AB}+\mathrm{B} \text { (slow) } \\ & \mathrm{A}+\mathrm{B} \rightarrow \mathrm{AB} \text { (fast) } \end{aligned}

The overall order of the reaction is:

View answer and explanation

Correct option: A

1.5

Option A (1.5) is correct because the rate law is determined by the slow step, and the concentration of the intermediate A is found using the equilibrium of the fast step, resulting in an overall order of 1.5.

2 Easy

2 of 301

Remembering +4 | -1

For the first order reaction with the rate constant

k

, which expression gives the rate half-life period?

(Initial\mathrm{ }conc.\mathrm{ } = a)

View answer and explanation

Correct option: D

\frac{{0.693}}{k}

Option D (

\frac{{0.693}}{k}

) is correct because the half-life of a first-order reaction is given by the formula

t_{1/2} = \frac{{0.693}}{k}

3 Medium

3 of 301

Understanding +4 | -1

Which of the following is a zero order reaction?

View answer and explanation

Correct option: A

2{\text{N}}{{\text{H}}_3}\left( {\text{g}} \right)\xrightarrow[{{\text{Pt catalyst}}}]{{1130\,{\text{K}}}}{{\text{N}}_{\text{2}}}\left( {\text{g}} \right) + 3{{\text{H}}_{\text{2}}}\left( {\text{g}} \right)

(Reactant

\mathrm{NH}_3

is strongly adsorbed

Option A (

2{\text{N}}{{\text{H}}_3}\left( {\text{g}} \right)\xrightarrow[{{\text{Pt catalyst}}}]{{1130{\,\text{K}}}}{{\text{N}}_{ ext{2}}}\left( {\text{g}} \right) + 3{{\text{H}}_{ ext{2}}}\left( {\text{g}} \right)

(Reactant

\mathrm{NH}_3

is strongly adsorbed) is correct because the decomposition of ammonia on a platinum surface at high pressure is a zero-order reaction due to the surface being saturated with ammonia.

4 Easy

4 of 301

Analyzing +4 | -1

For a certain reaction involving a single reactant, it is found that

C_0 \sqrt{T}

is constant, where

C_0

is the initial concentration of the reactant and

T

is the half-life. What is the order of the reaction?

View answer and explanation

Correct option: D

Option D (3) is correct because the rate law can be determined from the given relationship between initial concentration and half-life, leading to a third-order reaction.

5 Easy

5 of 301

Remembering +4 | -1

Arrhenius equation is

View answer and explanation

Correct option: C

k = A{e^{ - {E_a}/RT}}

Option C (

k = A{e^{ - {E_a}/RT}}

) is the correct Arrhenius equation, which relates the rate constant of a reaction to temperature and activation energy.

6 Medium

6 of 301

Application +4 | -1

The energy of activation for an uncatalysed reaction is

100 \mathrm{~kJ/mol}.

Presence of a catalyst lowers the energy of activation by

75 \%

. The

\log _{10} \frac{K_2}{K_1}

of the ratio of rate constant of catalysed and uncatalysed reactions at

27^{\circ} \mathrm{C}

is?

Assume the frequency factor is same for both reactions. (Given

2.303 \times 8.314=19.147

)

View answer and explanation

Correct option: A

13.05

Option A (13.05) is correct because it is the result of calculating the ratio of rate constants using the Arrhenius equation and the given activation energies.

7 Easy

7 of 301

Remembering +4 | -1

The rate at which a substance reacts depends on its

View answer and explanation

Correct option: D

Active mass

Option D (Active mass) is correct because the rate of a reaction is directly proportional to the active masses (effective concentrations) of the reactants.

8 Medium

8 of 301

Application +4 | -1

A first order reaction has a rate constant

1.15 \times {10^{ - 3}}{S^{ - 1}}

. How long will 5g of this reactant take to reduce to 3g (given log 1.667 = 0.2219)

View answer and explanation

Correct option: B

444 S

Option B (444 S) is correct because the time is calculated using the first-order kinetics equation with the given rate constant and initial/final amounts.

9 Medium

9 of 301

Application +4 | -1

For the reaction,

\mathrm{A}(\mathrm{g}) \rightarrow \mathrm{B}(\mathrm{g})+\mathrm{C}(\mathrm{g})

. The initial pressure was

\mathrm{P}_0

while pressure after time '

\mathrm{t}

' was

\mathrm{P}_{\mathrm{t}}

. The rate constant

\mathrm{k}

will be given by:

View answer and explanation

Correct option: C

\mathrm{k}=\frac{2.303}{\mathrm{t}} \log \frac{\mathrm{P}_0}{2 \mathrm{P}_0-\mathrm{P}_{\mathrm{t}}}

Option C (

\mathrm{k}=\frac{2.303}{\mathrm{t}} \log \frac{\mathrm{P}_0}{2 \mathrm{P}_0-\mathrm{P}_{\mathrm{t}}}

) is correct because it correctly applies the integrated rate law for a first-order gas-phase reaction.

10 Hard

10 of 301

Application +4 | -1

For a reaction of order

n,

the integrated form of the rate equation is

(n-1) \cdot K \cdot t=\left(C_0\right)^{1-n}-(C)^{1-n},

where

C_0

and

C

are the values of the reactant concentration at the start and after time '

t

'. What is the relationship between

t_{3 / 4}

and

t_{1 / 2},

where

t_{3 / 4}

is the time required for

C

to become

C_0 / 4.

View answer and explanation

Correct option: A

t_{3 / 4}=t_{1 / 2} \cdot\left[2^{n-1}+1\right]

The correct answer is

t_{3 / 4}=t_{1 / 2} \cdot\left[2^{n-1}+1\right]

because it is derived from the integrated rate equation for a reaction of order n.

11 Easy

11 of 301

Remembering +4 | -1

The temperature coefficient of a reaction is:

View answer and explanation

Correct option: C

The ratio of rate constant differing by

10^\circ C

, preferably

35^\circ C\;and\;25^\circ C

Option C is correct because the temperature coefficient is defined as the ratio of rate constants at two temperatures differing by 10°C, often measured at 35°C and 25°C.

12 Medium

12 of 301

Application +4 | -1

For the reaction

2 \mathrm{N}_2 \mathrm{O}_5 \rightarrow 4 \mathrm{NO}_2+\mathrm{O}_2

rate & rate constant are

1.02 \times 10^{-4}

and

3.4 \times 10^{-5} \mathrm{sec}^{-1}

respectively then concentration of

\mathrm{N}_2 \mathrm{O}_5

at that time will be:

View answer and explanation

Correct option: B

Option B (3) is correct because the concentration of N2O5 is calculated directly from the rate law, given the rate and rate constant.

13 Easy

13 of 301

Application +4 | -1

For the reaction,

2A + B \to products

, the active mass of B is kept constant, and that of A is doubled. The rate of reaction will be then

View answer and explanation

Correct option: C

Increase 4 times

Option C (Increase 4 times) is correct because the rate of the reaction is proportional to the square of the concentration of reactant A.

14 Easy

14 of 301

Understanding +4 | -1

Which one of the following reactions is a true first order reaction?

View answer and explanation

Correct option: C

Decomposition of

{N}_2 {O}

Option A (Alkaline hydrolysis of ethyl acetate) is incorrect. Option B (Acid catalyst hydrolysis of ethyl acetate) is incorrect. Option C (Decomposition of

{N}_2 {O}

) is correct because it follows first-order kinetics. Option D (Decomposition of gaseous ammonia on a hot platinum surface) is incorrect.

15 Easy

15 of 301

Understanding +4 | -1

According to collision theory of reaction rates:

View answer and explanation

Correct option: D

Rate of reaction is directly proportional to collision frequency

Option D is correct because, according to collision theory, the rate of a reaction is directly proportional to the frequency of collisions between reactant molecules.

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16 Medium

16 of 301

Application +4 | -1

The value of rate constant for the above reaction is:

View answer and explanation

Correct option: D

None of these

The correct answer is None of these because the rate constant cannot be determined without more information about the rate of reaction.

17 Hard

17 of 301

Analyzing +4 | -1

The temperature coefficients of two reactions are 2 and 3 respectively. Which would be correct for these reactions?

View answer and explanation

Correct option: A

E_{a_1} < E_{a_2}

Option A (

E_{a_1} < E_{a_2}

) is correct because a higher temperature coefficient indicates a greater sensitivity to temperature changes, implying a higher activation energy.

18 Hard

18 of 301

Application +4 | -1

Half-life of two samples is 0.1 and 0.8 s. Their respective concentration is 400 and 50 respectively.

The order of reaction is

View answer and explanation

Correct option: B

Option B (2) is correct because the order of the reaction is calculated to be 2 using the half-life equation and the given concentrations.

19 Medium

19 of 301

Analyzing +4 | -1

STATEMENT-1: Active complex is an intermediate product.

STATEMENT-2 : Active complex is unstable with high vibrational energy.

View answer and explanation

Correct option: D

If STATEMENT-1 is FALSE and STATEMENT-2 is TRUE

Option D is correct because Statement-1 is false, as the active complex is an intermediate product, and Statement-2 is true, as the active complex is unstable with high vibrational energy.

20 Medium

20 of 301

Analyzing +4 | -1

Statement I For the reaction

\begin{aligned} & 2 \mathrm{KClO}_3 \longrightarrow 2 \mathrm{KCl}+3 \mathrm{O}_2 \\ & \frac{-d\left[\mathrm{KClO}_3\right]}{d t}=\frac{2}{3} \frac{d\left[\mathrm{O}_2\right]}{d t} \end{aligned}

Statement II If average rate of formation of

\mathrm{O}_2

0.01 \mathrm{~mol}

\mathrm{min}^{-1}

, rate of disappearance of

\mathrm{KClO}_3

0.03 \mathrm{~mol} \mathrm{~min}^{-1}

View answer and explanation

Correct option: C

Statement I is correct but Statement II is incorrect

The correct answer is C because Statement I is correct based on the stoichiometry of the reaction, but Statement II is incorrect as the rate of disappearance of KClO₃ should be 0.02 mol min⁻¹ when the rate of formation of O₂ is 0.03 mol min⁻¹.

21 Medium

21 of 301

Analyzing +4 | -1

For the reaction

A+B \rightarrow 2 C+D,

which of the following statement are incorrect?

View answer and explanation

Correct option: A

\text{Rate of disappearance of }B =2 \times \text{rate of appearance of }C

The correct answer is A (Rate of disappearance of B = 2 x rate of appearance of C) because, according to the stoichiometry of the reaction, the rate of disappearance of B should be half the rate of appearance of C.

22 Easy

22 of 301

Remembering +4 | -1

Effect of temperature on reaction rate is given by

View answer and explanation

Correct option: B

Arrhenius equation

Option B (Arrhenius equation) is correct because the Arrhenius equation describes the relationship between temperature and reaction rate.

23 Hard

23 of 301

Analyzing +4 | -1

In the following reaction;

xA \to yB

{\log _{10}}\left[ { - \frac{{d\left[ A \right]}}{{dt}}} \right] = {\log _{10}}\left[ {\frac{{d\left[ B \right]}}{{dt}}} \right] + 0.3010

A and B respectively can be

View answer and explanation

Correct option: C

{C_2}{H_4}

and

{C_4}{H_8}

Option C is correct because the stoichiometry of the reaction is 2A -> B, which corresponds to 2C2H4 -> C4H8.

24 Easy

24 of 301

Analyzing +4 | -1

The rate constant

(K)

for the reaction

2A + B \to product

  was found to be

2.5 \times {10^{ - 5}}\;\mathrm{litre}\;\mathrm{mo}{\mathrm{l}^{ - 1}}\;{\sec ^{ - 1}}\;\;after\;\;15\sec ,\;2.60 \times {10^{ - 5}}\;\mathrm{litre}\;\mathrm{mo}{\mathrm{l}^{ - 1}}\;{\sec ^{ - 1}}\;\mathrm{after}\;\;30\sec

and

2.55 \times {10^{ - 5}}\;\mathrm{litre}\;\mathrm{mo}{\mathrm{l}^{ - 1}}\;{\sec ^{ - 1}}\;\mathrm{after}\;\;50\;\mathrm{sec}\mathrm{.}

The order of reaction is:

View answer and explanation

Correct option: A

Option A (2) is correct because the rate constant K remains approximately constant over time, and the units of K (litre mol^-1 sec^-1) indicate a second-order reaction.

25 Medium

25 of 301

Analyzing +4 | -1

Assertion: Acid catalyzed of ethyl acetate is a first order reaction.

Reason: Water does not take part in the reaction.

View answer and explanation

Correct option: C

If Assertion is True but the Reason is False

Option C (If Assertion is True but the Reason is False) is correct because the acid-catalyzed hydrolysis of ethyl acetate is pseudo-first order, but water does participate in the reaction.

26 Medium

26 of 301

Understanding +4 | -1

The order of a reaction with rate equal to

k\;C_A^{3/2}\;C_B^{ - 1/2}

View answer and explanation

Correct option: A

Option A (1) is correct because the order of the reaction is the sum of the exponents of the concentration terms in the rate law, which in this case is 3/2 + (-1/2) = 1.

27 Easy

27 of 301

Understanding +4 | -1

For a first order reaction, the half-life period is independent of

View answer and explanation

Correct option: C

Initial concentration

Option C (Initial concentration) is correct because the half-life of a first-order reaction is independent of the initial concentration of the reactant.

28 Medium

28 of 301

Understanding +4 | -1

STATEMENT 1 : Product can form only when the required orientation and energy conditions are met
STATEMENT-2 : All collisions between reactants yield the desired product.

View answer and explanation

Correct option: C

If STATEMENT-1 is TRUE and STATEMENT-2 is FALSE

Option C (If STATEMENT-1 is TRUE and STATEMENT-2 is FALSE) is correct because product formation requires specific orientation and energy, but not all collisions lead to product formation.

29 Medium

29 of 301

Application +4 | -1

For a first order reaction rate constant is given as,

\log \,\,K = 14 - \frac{{1.2 \times {{10}^4}}}{T}

, then what will be value of

'T'

if its half-life is

6.93 \times {10^{ - 3}}\,\,\min

View answer and explanation

Correct option: B

1000 K

Option B (1000 K) is correct because the temperature is calculated using the Arrhenius equation and the given half-life.

30 Hard

30 of 301

Application +4 | -1

The thermal decomposition of a compound is of first order. If a sample of the compound decompose 50% in 120 min. What time will it take to undergo 90% decomposition?

View answer and explanation

Correct option: A

Nearly 400 min

The correct answer is Nearly 400 min because the time for 90% decomposition is calculated using the first-order kinetics equation.

Revision notes and key takeaways

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Key Takeaways

✓ This set contains 301 single-correct-answer MCQs on CHEMICAL KINETICS.
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