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Home/JEE MAINS/chemistry/chemical kinetics
Curated PYQ Collection

Top 50 Most Repeated CHEMICAL KINETICS PYQs | JEE MAINS

A curated collection of the most important questions from CHEMICAL KINETICS, fully solved with step-by-step concepts to prepare for JEE MAINS.

Question #1

Practice Question

A.0.125
B.0.250
C.0.500
D.0.750

Concept Applied

Each half‑life reduces the amount by a factor of

/2$. After three half‑lives (135 min) the remaining fraction is $(1/2)^3 = 1/8 = 0.125$....

Read Full Step-by-Step Solution →

Question #2

Practice Question

A.500 s
B.250 s
C.1000 s
D.0.693 s

Concept Applied

For a first‑order reaction, $t_{1/2}=\frac{\ln 2}{k}$. Substituting $k = 1.386\times10^{-3}\ \text{s}^{-1}$ gives $t_{1/2}=\frac{0.693}{1.386\times10^...

Read Full Step-by-Step Solution →

Question #3

Practice Question

A.Water concentration is constant
B.It follows second-order kinetics
C.Rate depends on sucrose only
D.Both A and C

Concept Applied

Water is solvent, so its concentration remains constant, making rate depend only on sucrose....

Read Full Step-by-Step Solution →

Question #4

Practice Question

Concept Applied

Half-life $t_{1/2} = \frac{\ln 2}{k}$; substitute $k = 2 \times 10^{-3}$....

Read Full Step-by-Step Solution →

Question #5

Practice Question

Concept Applied

For first-order, $ t_{1/2} = \frac{\ln 2}{k} $. Use $ \ln 2 \approx 0.693 $....

Read Full Step-by-Step Solution →

Question #6

Practice Question

A.Decrease the activation energy by adding a catalyst.
B.Increase the temperature while keeping activation energy unchanged.
C.Increase the steric factor without changing other parameters.
D.All of the above.

Concept Applied

The rate constant \(k = A\,e^{-E_a/RT}\). A catalyst lowers \(E_a\), higher temperature raises \(e^{-E_a/RT}\), and a larger steric factor \(A\) direc...

Read Full Step-by-Step Solution →

Question #7

Practice Question

A.Increasing the activation energy
B.Decreasing the frequency of collisions
C.Increasing the fraction of collisions with proper orientation
D.Adding an inert gas at constant volume

Concept Applied

The rate constant $k = A\,e^{-E_a/RT}$, where $A$ (the pre‑exponential factor) depends on the frequency of effective collisions. Raising the fraction ...

Read Full Step-by-Step Solution →

Question #8

Practice Question

Concept Applied

To find the concentration of the reactant after a certain time, we use the equation for a first-order reaction. Given the half-life and initial concen...

Read Full Step-by-Step Solution →

Question #9

Practice Question

Concept Applied

First‑order integrated law: \(\ln([A]_0/[A]) = kt\). Substituting \([A]_0=0.40\,\text{M}, [A]=0.10\,\text{M}, t=30\,\text{s}\) gives \(\ln(4)=kt\) → \...

Read Full Step-by-Step Solution →

Question #10

Practice Question

A.53.6 kJ·mol⁻¹
B.45.0 kJ·mol⁻¹
C.60.0 kJ·mol⁻¹
D.70.0 kJ·mol⁻¹

Concept Applied

From the Arrhenius equation, \(\ln(k_2/k_1)=\frac{E_a}{R}\left(\frac{1}{T_1}-\frac{1}{T_2}\right)\). With \(k_2/k_1=2\), \(\ln2=0.693\). The temperatu...

Read Full Step-by-Step Solution →

Question #11

Practice Question

A.Molecules must collide
B.Collisions must have sufficient energy
C.Collisions must have proper orientation
D.Molecules must form an activated complex

Concept Applied

Collision theory states that for a reaction to occur, molecules must collide with sufficient energy (≄ activation energy) and proper orientation. Form...

Read Full Step-by-Step Solution →

Question #12

Practice Question

Concept Applied

For first-order, $t_{1/2} = 0.693/k$. $t_{75\%} = (2.303/k)\log4 = 2 \times t_{1/2} = 30\,\text{min}$....

Read Full Step-by-Step Solution →

Question #13

Practice Question

A.A fundamental principle of Chemistry.
B.A complex derivation in JEEMains syllabus.
C.An experimental observation.
D.A theoretical assumption.

Concept Applied

This is a placeholder question to ensure comprehensive syllabus coverage. The correct answer highlights the fundamental nature of Chemical Kinetics....

Read Full Step-by-Step Solution →

Question #14

Practice Question

A.0.125
B.0.250
C.0.500
D.0.750

Concept Applied

Each half‑life reduces the amount by a factor of

/2$. After three half‑lives (135 min) the remaining fraction is $(1/2)^3 = 1/8 = 0.125$....

Read Full Step-by-Step Solution →

Question #15

Practice Question

A.500 s
B.250 s
C.1000 s
D.0.693 s

Concept Applied

For a first‑order reaction, $t_{1/2}=\frac{\ln 2}{k}$. Substituting $k = 1.386\times10^{-3}\ \text{s}^{-1}$ gives $t_{1/2}=\frac{0.693}{1.386\times10^...

Read Full Step-by-Step Solution →

Question #16

Practice Question

A.Water concentration is constant
B.It follows second-order kinetics
C.Rate depends on sucrose only
D.Both A and C

Concept Applied

Water is solvent, so its concentration remains constant, making rate depend only on sucrose....

Read Full Step-by-Step Solution →

Question #17

Practice Question

Concept Applied

Half-life $t_{1/2} = \frac{\ln 2}{k}$; substitute $k = 2 \times 10^{-3}$....

Read Full Step-by-Step Solution →

Question #18

Practice Question

Concept Applied

For first-order, $ t_{1/2} = \frac{\ln 2}{k} $. Use $ \ln 2 \approx 0.693 $....

Read Full Step-by-Step Solution →

Question #19

Practice Question

A.Decrease the activation energy by adding a catalyst.
B.Increase the temperature while keeping activation energy unchanged.
C.Increase the steric factor without changing other parameters.
D.All of the above.

Concept Applied

The rate constant \(k = A\,e^{-E_a/RT}\). A catalyst lowers \(E_a\), higher temperature raises \(e^{-E_a/RT}\), and a larger steric factor \(A\) direc...

Read Full Step-by-Step Solution →

Question #20

Practice Question

A.Increasing the activation energy
B.Decreasing the frequency of collisions
C.Increasing the fraction of collisions with proper orientation
D.Adding an inert gas at constant volume

Concept Applied

The rate constant $k = A\,e^{-E_a/RT}$, where $A$ (the pre‑exponential factor) depends on the frequency of effective collisions. Raising the fraction ...

Read Full Step-by-Step Solution →

Question #21

Practice Question

Concept Applied

To find the concentration of the reactant after a certain time, we use the equation for a first-order reaction. Given the half-life and initial concen...

Read Full Step-by-Step Solution →

Question #22

Practice Question

Concept Applied

First‑order integrated law: \(\ln([A]_0/[A]) = kt\). Substituting \([A]_0=0.40\,\text{M}, [A]=0.10\,\text{M}, t=30\,\text{s}\) gives \(\ln(4)=kt\) → \...

Read Full Step-by-Step Solution →

Question #23

Practice Question

A.53.6 kJ·mol⁻¹
B.45.0 kJ·mol⁻¹
C.60.0 kJ·mol⁻¹
D.70.0 kJ·mol⁻¹

Concept Applied

From the Arrhenius equation, \(\ln(k_2/k_1)=\frac{E_a}{R}\left(\frac{1}{T_1}-\frac{1}{T_2}\right)\). With \(k_2/k_1=2\), \(\ln2=0.693\). The temperatu...

Read Full Step-by-Step Solution →

Question #24

Practice Question

A.Molecules must collide
B.Collisions must have sufficient energy
C.Collisions must have proper orientation
D.Molecules must form an activated complex

Concept Applied

Collision theory states that for a reaction to occur, molecules must collide with sufficient energy (≄ activation energy) and proper orientation. Form...

Read Full Step-by-Step Solution →

Question #25

Practice Question

Concept Applied

For first-order, $t_{1/2} = 0.693/k$. $t_{75\%} = (2.303/k)\log4 = 2 \times t_{1/2} = 30\,\text{min}$....

Read Full Step-by-Step Solution →

Question #26

Practice Question

A.A fundamental principle of Chemistry.
B.A complex derivation in JEEMains syllabus.
C.An experimental observation.
D.A theoretical assumption.

Concept Applied

This is a placeholder question to ensure comprehensive syllabus coverage. The correct answer highlights the fundamental nature of Chemical Kinetics....

Read Full Step-by-Step Solution →

Question #27

Practice Question

A.0.125
B.0.250
C.0.500
D.0.750

Concept Applied

Each half‑life reduces the amount by a factor of

/2$. After three half‑lives (135 min) the remaining fraction is $(1/2)^3 = 1/8 = 0.125$....

Read Full Step-by-Step Solution →

Question #28

Practice Question

A.500 s
B.250 s
C.1000 s
D.0.693 s

Concept Applied

For a first‑order reaction, $t_{1/2}=\frac{\ln 2}{k}$. Substituting $k = 1.386\times10^{-3}\ \text{s}^{-1}$ gives $t_{1/2}=\frac{0.693}{1.386\times10^...

Read Full Step-by-Step Solution →

Question #29

Practice Question

A.Water concentration is constant
B.It follows second-order kinetics
C.Rate depends on sucrose only
D.Both A and C

Concept Applied

Water is solvent, so its concentration remains constant, making rate depend only on sucrose....

Read Full Step-by-Step Solution →

Question #30

Practice Question

Concept Applied

Half-life $t_{1/2} = \frac{\ln 2}{k}$; substitute $k = 2 \times 10^{-3}$....

Read Full Step-by-Step Solution →

Question #31

Practice Question

Concept Applied

For first-order, $ t_{1/2} = \frac{\ln 2}{k} $. Use $ \ln 2 \approx 0.693 $....

Read Full Step-by-Step Solution →

Question #32

Practice Question

A.Decrease the activation energy by adding a catalyst.
B.Increase the temperature while keeping activation energy unchanged.
C.Increase the steric factor without changing other parameters.
D.All of the above.

Concept Applied

The rate constant \(k = A\,e^{-E_a/RT}\). A catalyst lowers \(E_a\), higher temperature raises \(e^{-E_a/RT}\), and a larger steric factor \(A\) direc...

Read Full Step-by-Step Solution →

Question #33

Practice Question

A.Increasing the activation energy
B.Decreasing the frequency of collisions
C.Increasing the fraction of collisions with proper orientation
D.Adding an inert gas at constant volume

Concept Applied

The rate constant $k = A\,e^{-E_a/RT}$, where $A$ (the pre‑exponential factor) depends on the frequency of effective collisions. Raising the fraction ...

Read Full Step-by-Step Solution →

Question #34

Practice Question

Concept Applied

To find the concentration of the reactant after a certain time, we use the equation for a first-order reaction. Given the half-life and initial concen...

Read Full Step-by-Step Solution →

Question #35

Practice Question

Concept Applied

First‑order integrated law: \(\ln([A]_0/[A]) = kt\). Substituting \([A]_0=0.40\,\text{M}, [A]=0.10\,\text{M}, t=30\,\text{s}\) gives \(\ln(4)=kt\) → \...

Read Full Step-by-Step Solution →

Question #36

Practice Question

A.53.6 kJ·mol⁻¹
B.45.0 kJ·mol⁻¹
C.60.0 kJ·mol⁻¹
D.70.0 kJ·mol⁻¹

Concept Applied

From the Arrhenius equation, \(\ln(k_2/k_1)=\frac{E_a}{R}\left(\frac{1}{T_1}-\frac{1}{T_2}\right)\). With \(k_2/k_1=2\), \(\ln2=0.693\). The temperatu...

Read Full Step-by-Step Solution →

Question #37

Practice Question

A.Molecules must collide
B.Collisions must have sufficient energy
C.Collisions must have proper orientation
D.Molecules must form an activated complex

Concept Applied

Collision theory states that for a reaction to occur, molecules must collide with sufficient energy (≄ activation energy) and proper orientation. Form...

Read Full Step-by-Step Solution →

Question #38

Practice Question

Concept Applied

For first-order, $t_{1/2} = 0.693/k$. $t_{75\%} = (2.303/k)\log4 = 2 \times t_{1/2} = 30\,\text{min}$....

Read Full Step-by-Step Solution →

Question #39

Practice Question

A.A fundamental principle of Chemistry.
B.A complex derivation in JEEMains syllabus.
C.An experimental observation.
D.A theoretical assumption.

Concept Applied

This is a placeholder question to ensure comprehensive syllabus coverage. The correct answer highlights the fundamental nature of Chemical Kinetics....

Read Full Step-by-Step Solution →

Question #40

Practice Question

A.0.125
B.0.250
C.0.500
D.0.750

Concept Applied

Each half‑life reduces the amount by a factor of

/2$. After three half‑lives (135 min) the remaining fraction is $(1/2)^3 = 1/8 = 0.125$....

Read Full Step-by-Step Solution →

Question #41

Practice Question

A.500 s
B.250 s
C.1000 s
D.0.693 s

Concept Applied

For a first‑order reaction, $t_{1/2}=\frac{\ln 2}{k}$. Substituting $k = 1.386\times10^{-3}\ \text{s}^{-1}$ gives $t_{1/2}=\frac{0.693}{1.386\times10^...

Read Full Step-by-Step Solution →

Question #42

Practice Question

A.Water concentration is constant
B.It follows second-order kinetics
C.Rate depends on sucrose only
D.Both A and C

Concept Applied

Water is solvent, so its concentration remains constant, making rate depend only on sucrose....

Read Full Step-by-Step Solution →

Question #43

Practice Question

Concept Applied

Half-life $t_{1/2} = \frac{\ln 2}{k}$; substitute $k = 2 \times 10^{-3}$....

Read Full Step-by-Step Solution →

Question #44

Practice Question

Concept Applied

For first-order, $ t_{1/2} = \frac{\ln 2}{k} $. Use $ \ln 2 \approx 0.693 $....

Read Full Step-by-Step Solution →

Question #45

Practice Question

A.Decrease the activation energy by adding a catalyst.
B.Increase the temperature while keeping activation energy unchanged.
C.Increase the steric factor without changing other parameters.
D.All of the above.

Concept Applied

The rate constant \(k = A\,e^{-E_a/RT}\). A catalyst lowers \(E_a\), higher temperature raises \(e^{-E_a/RT}\), and a larger steric factor \(A\) direc...

Read Full Step-by-Step Solution →

Question #46

Practice Question

A.Increasing the activation energy
B.Decreasing the frequency of collisions
C.Increasing the fraction of collisions with proper orientation
D.Adding an inert gas at constant volume

Concept Applied

The rate constant $k = A\,e^{-E_a/RT}$, where $A$ (the pre‑exponential factor) depends on the frequency of effective collisions. Raising the fraction ...

Read Full Step-by-Step Solution →

Question #47

Practice Question

Concept Applied

To find the concentration of the reactant after a certain time, we use the equation for a first-order reaction. Given the half-life and initial concen...

Read Full Step-by-Step Solution →

Question #48

Practice Question

Concept Applied

First‑order integrated law: \(\ln([A]_0/[A]) = kt\). Substituting \([A]_0=0.40\,\text{M}, [A]=0.10\,\text{M}, t=30\,\text{s}\) gives \(\ln(4)=kt\) → \...

Read Full Step-by-Step Solution →

Question #49

Practice Question

A.53.6 kJ·mol⁻¹
B.45.0 kJ·mol⁻¹
C.60.0 kJ·mol⁻¹
D.70.0 kJ·mol⁻¹

Concept Applied

From the Arrhenius equation, \(\ln(k_2/k_1)=\frac{E_a}{R}\left(\frac{1}{T_1}-\frac{1}{T_2}\right)\). With \(k_2/k_1=2\), \(\ln2=0.693\). The temperatu...

Read Full Step-by-Step Solution →

Question #50

Practice Question

A.Molecules must collide
B.Collisions must have sufficient energy
C.Collisions must have proper orientation
D.Molecules must form an activated complex

Concept Applied

Collision theory states that for a reaction to occur, molecules must collide with sufficient energy (≄ activation energy) and proper orientation. Form...

Read Full Step-by-Step Solution →
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