Chemical Kinetics NEET Previous Year Question Papers (2021 - 2025)

Chemical Kinetics NEET Previous Year Questions (2021–2026): Chapter Importance and Weightage

Chemical Kinetics assists the NEET aspirants to grasp important topics like the Arrhenius equation, collision theory, rate law, and mechanism of reactions. This chapter is among the most important in the NEET Chemistry syllabus, with questions being asked almost every year. Answering Chemical Kinetics NEET PYQs can help aspirants get familiar with important topics as well as enhance their problem-solving ability. The following table gives an idea about the number of questions asked in previous years from Chemical Kinetics.

Most Repeated Chemical Kinetics NEET PYQ

Numerical-based questions from Chemical Kinetics appear in the NEET exam. To solve them in less time, an effective NEET preparation timetable is important. The timetable should include 2-3 hours daily for solving the NEET question paper. Provided below are a few NEET chemical kinetics previous year questions with solutions. Going through them makes students familiar with the question pattern

Question 1: If the half-life $(t_{1/2})$ for a first-order reaction is $1\ \text{minute}$, then the time required for $99.9%$ completion of the reaction is closest to: (NEET 2025)

Options
1. $10\ \text{minutes}$
2. $2\ \text{minutes}$
3. $4\ \text{minutes}$
4. $5\ \text{minutes}$

Answer: For a first-order reaction:
$t = \dfrac{6.9}{k}$ for $\sim 99.9%$ completion (more accurately, $t = \dfrac{6.91}{k}$)

Also, half-life is given by:
$t_{1/2} = \dfrac{0.693}{k} \Rightarrow k = \dfrac{0.693}{1} = 0.693$

$\Rightarrow t = \dfrac{6.91}{0.693} \approx 10\ \text{min}$

Hence, the correct answer is option $1)$ $10\ \text{minutes}$.

Question 2: If the rate constant of a reaction is $0.03\ \text{s}^{-1}$, how much time does it take for $7.2\ \text{mol L}^{-1}$ concentration of the reactant to get reduced to $0.9\ \text{mol L}^{-1}$? (Given: $\log 2 = 0.3$) (NEET 2025)

Options
1. $21.0\ \text{s}$
2. $69.3\ \text{s}$
3. $23.1\ \text{s}$
4. $210\ \text{s}$

Answer: Given that
Initial concentration $[R]_0 = 7.2\ \text{mol L}^{-1}$
Final concentration $[R] = 0.9\ \text{mol L}^{-1}$
Rate constant $k = 0.03\ \text{s}^{-1}$

Since units of $k$ are $\text{s}^{-1}$, it is a first-order reaction.

Formula:
$t = \dfrac{2.303}{k} \log \left( \dfrac{[R]_0}{[R]} \right)$

Substitute:
$t = \dfrac{2.303}{0.03} \log \left( \dfrac{7.2}{0.9} \right)$

$t = \dfrac{2.303}{0.03} \log (8)$

Now,
$\log(8) = \log(2^3) = 3 \log 2 = 3 \times 0.3 = 0.9$

So,
$t = \dfrac{2.303}{0.03} \times 0.9 = 76.77 \times 0.9 = 69.093\ \text{s}$

$\approx 69.3\ \text{s}$

Hence, the correct answer is option $2)$ $69.3\ \text{s}$.

Question 3: Which plot of In k vs 1/T is consistent with the Arrhenius equation? (NEET 2024)

Options

3.

4.

Answer:

The Arrhenius equation is given as

$k = A e^{-\dfrac{E_a}{RT}}$

Taking logarithm

$\ln k = \ln A - \dfrac{E_a}{R}\left(\dfrac{1}{T}\right)$

Thus a plot of $\ln k$ vs $\dfrac{1}{T}$ gives a straight line

slope $= -\dfrac{E_a}{R}$

intercept $= \ln A$

Hence, the correct answer is option (4)

Question 7: The given graph is a representation of the kinetics of a reaction

The $y$ and $x$ axes for zero and first-order reactions respectively are: (NEET 2022)

Options

1. zero order $(y=\text{concentration}\ x=\text{time})$ first order $(y=\text{rate constant}\ x=\text{concentration})$

2. zero order $(y=\text{rate}\ x=\text{concentration})$ first order $(y=t_{1/2}\ x=\text{concentration})$

3. zero order $(y=\text{rate}\ x=\text{concentration})$ first order $(y=\text{rate}\ x=t_{1/2})$

4. zero order $(y=\text{concentration}\ x=\text{time})$ first order $(y=t_{1/2}\ x=\text{concentration})$

Answer:

For zero order reaction
$\text{Rate} \propto [A]^0$
$\Rightarrow \text{Rate} = k$

For first order reaction
$t_{1/2} = \dfrac{\ln 2}{k}$

Hence correct answer option $(2)$

Question 8: The slope of Arrhenius plot $\ln k$ vs $\dfrac{1}{T}$ for a first-order reaction is $-5 \times 10^3\ \text{K}$. The value of $E_a$ is: (NEET 2021)

Given $R = 8.314\ \text{J K}^{-1}\text{mol}^{-1}$

Options

1. $41.5\ \text{kJ mol}^{-1}$
2. $83.0\ \text{kJ mol}^{-1}$
3. $166\ \text{kJ mol}^{-1}$
4. $-83\ \text{kJ mol}^{-1}$

Answer:

$\ln k = \ln A - \dfrac{E_a}{R}\left(\dfrac{1}{T}\right)$

Slope $m = -\dfrac{E_a}{R}$

$-5 \times 10^3 = -\dfrac{E_a}{8.314}$

$\Rightarrow E_a = 5 \times 10^3 \times 8.314$

$E_a = 41.5\ \text{kJ mol}^{-1}$

Hence correct answer option $(1)$

Question 9: An increase in the concentration of the reactants of a reaction leads to a change in: (NEET 2020)

Options

1. Collision frequency
2. Activation energy
3. Heat of reaction
4. Threshold energy

Answer:

Increase in concentration increases number of collisions

Hence correct answer option $(1)$

Question 10: The rate constant for a first-order reaction is $4.606 \times 10^{-3}\ \text{s}^{-1}$. The time required to reduce $2\ \text{g}$ of reactant to $0.2\ \text{g}$ is: (NEET 2020)

Options

1. $1000\ \text{s}$
2. $100\ \text{s}$
3. $200\ \text{s}$
4. $500\ \text{s}$

Answer:

$kt = \ln\left(\dfrac{A_0}{A_t}\right)$

$4.606 \times 10^{-3} t = 2.303 \log\left(\dfrac{2}{0.2}\right)$

$= 2.303$

$\Rightarrow t = \dfrac{2.303}{4.606 \times 10^{-3}}$

$t = 500\ \text{s}$

Hence correct answer option $(4)$

High‑Yield Chemical Kinetics Important NEET 2027 Topics

Chemical Kinetics is a scoring unit in chemistry. It is a high weightage NEET chemistry chapter with consistently asked questions in previous years. Chemical kinetics NEET PYQ includes questions on how reactions occur and the different factors affecting them. Students thinking about how to study chemistry for NEET should start with this unit. Given below are a few important topics from this unit

Tips to Solve Chemical Kinetics NEET 2027 Questions Quickly and Accurately

Solving previous year NEET questions regularly builds confidence. It helps students understand the types of questions asked in the exam. Given below are a few tips that they can use to solve NEET chemical kinetics previous year questions.

1. Students have to understand how to obtain rate laws from the rate-determining step. Accessing the NEET chemistry mock test improves score and speed.
2. Aspirants can start by solving the important NEET chemistry questions to make their preparation strong
3. Learn how to determine the order of a reaction from experimental data and not just by stoichiometry.
4. Solve NEET PYQ chemical kinetics by using the NEET chemistry question paper.
5. Get familiar with the rate equations for zero, first, and second-order reactions. Study only from the Chemistry books for NEET to avoid confusion.
6. Must practice these top 75 repeated chemistry questions in PYQs to strengthen NEET 2027 preparation.
7. Understand the role of activation energy and how it plays a part in the rate determination. Try to apply the Arrhenius equation to the temperature changes.
8. Prepare flashcards of important formulas for NEET chemistry. This helps to answer NEET chemical kinetics previous year questions confidently.