Chemical Kinetics NEET Previous Year Question Papers (2021 - 2026)

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.

Why Solve Chemical Kinetics NEET Previous Year Questions?

Chemical Kinetics includes some topics based on formulas where continuous practice can definitely help in improving calculation speed and accuracy. Solving questions from previous years can assist candidates in:

• Understanding the NEET question pattern.
• Recognising commonly asked Chemical Kinetics topics.
• Practising numerical questions in a time-bound manner.
• Enhancing the application of integrated rate equations.
• Learning the concept of using the Arrhenius equation.
• Finding out errors in calculations regarding units and logarithms.
• Improving the concepts of order, molecularity, and rate law.

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 $1$ minute, then the time required for $99.9%$ completion of the reaction is closest to: (NEET 2025)

Options

1. $10$ minutes
2. $2$ minutes
3. $4$ minutes
4. $5$ minutes

Answer: For a first-order reaction, the time required for approximately $99.9%$ completion is given by:

$t \approx \frac{6.91}{k}$

Also, the half-life is given by:

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

Given $t_{1/2} = 1$ minute,

$1 = \frac{0.693}{k}$

$\Rightarrow k = 0.693\ \text{min}^{-1}$

Therefore,

$t = \frac{6.91}{0.693}$

$\Rightarrow t \approx 10\ \text{min}$

Hence, the correct answer is Option 1) $10$ 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: For a first-order reaction,

$t = \frac{2.303}{k}\log\left(\frac{[R]_0}{[R]_t}\right)$

Given,

$k = 0.03\ \text{s}^{-1}$

$[R]_0 = 7.2\ \text{mol L}^{-1}$

$[R]_t = 0.9\ \text{mol L}^{-1}$

Therefore,

$t = \frac{2.303}{0.03}\log\left(\frac{7.2}{0.9}\right)$

$t = \frac{2.303}{0.03}\log 8$

Since $\log 8 = 3\log 2 = 3 \times 0.3 = 0.9$,

$t = \frac{2.303 \times 0.9}{0.03}$

$t = 69.09\ \text{s} \approx 69.3\ \text{s}$

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 by

$k = Ae^{-\frac{E_a}{RT}}$

Taking the natural logarithm on both sides,

$\ln k = \ln A - \frac{E_a}{RT}$

Thus, a plot of $\ln k$ versus $1/T$ gives a straight line with

$\text{slope} = -\frac{E_a}{R}$

and

$\text{intercept} = \ln A$

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

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 a zero-order reaction,

$\text{Rate} \propto [A]^0$

$\Rightarrow \text{Rate} = k$

For a first-order reaction,

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

Hence, the correct answer is Option 2.

Question 8: The slope of Arrhenius plot $\ln k$ vs. $\frac{1}{T}$ 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

The Arrhenius equation in logarithmic form is

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

Comparing this with the equation of a straight line, $y = mx + c$, the slope is

$m = -\frac{E_a}{R}$

Given

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

Therefore,

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

$E_a = 41,570\ \text{J mol}^{-1}$

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

Hence, the correct answer is Option 1 — $41.5\ \text{kJ mol}^{-1}$.

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:

An increase in concentration increases the 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

For a first-order reaction,

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

Given,

$A_0 = 2\ \text{g}$, $A_t = 0.2\ \text{g}$ and $k = 4.606 \times 10^{-3}\ \text{s}^{-1}$

Therefore,

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

$4.606 \times 10^{-3}t = 2.303\log(10)$

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

Hence,

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

$t = 500\ \text{s}$

Hence, the correct answer is Option 4) $500\ \text{s}$.

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.

Common Mistakes in Chemical Kinetics NEET Preparation

Not making these mistakes in Chemical Kinetics will help candidates enhance their performance in NEET 2027.

Misunderstanding Between Order and Molecularity

While order is derived through experiments using the rate law, molecularity is related to an elementary reaction.

Using Coefficients of Reaction Directly

The order of a reaction is not usually calculated using the chemical equation of a reaction but rather using the rate law or experimental data.

Mistaking Units of k

Units of (k) are affected by the order of the reaction; hence, a frequent mistake in numerical questions asked in NEET.

Confusing the Two Half-Life Formulas

First-order half-life is not dependent on the initial concentration, while zero-order half-life is dependent on the initial concentration.