Chemical Kinetics - NEET Previous Year Questions with Complete Solutions

Q: How many questions come from Chemical Kinetics in NEET every year?

Chemical Kinetics contributes 2–3 questions in NEET Chemistry almost every year, making it one of the most reliably tested chapters. Topics appearing most consistently include first order half-life, order of reaction determination from data, Arrhenius equation calculations, units of rate constant, and pseudo first-order reactions.

Q: What is the weightage of Chemical Kinetics in NEET Chemistry?

Chemical Kinetics carries approximately 5–8% weightage in NEET Chemistry, contributing 2–3 questions worth 8–12 marks. Along with Electrochemistry and Liquid Solutions, it is one of the three most consistently tested chapters from Class 12 Chemistry in NEET every year.

Q: What is the half-life of a first order reaction?

The half-life of a first order reaction is t½ = 0.693/k, where k is the rate constant. A key feature of first order reactions is that half-life is completely independent of initial concentration — it remains constant throughout the reaction. This is one of the most tested facts in Chemical Kinetics NEET questions.

Q: What is the difference between order and molecularity of a reaction?

Order of reaction is determined experimentally from the rate law — it can be zero, fractional, or any whole number, and applies to both elementary and complex reactions. Molecularity is a theoretical concept that applies only to elementary reactions — it is always a positive whole number (1, 2, or 3) representing the number of species colliding in a single step.

Q: How do I use the Arrhenius equation in NEET numericals?

For NEET, use the log form: log(k₂/k₁) = (Ea/2.303R) × (1/T₁ – 1/T₂), where T₁ is the lower temperature and T₂ is the higher temperature. Substitute R = 8.314 J/mol·K, temperatures in Kelvin, and solve for Ea or k₂. Always check that Ea comes out positive — if it is negative, you have reversed T₁ and T₂.

Team eSaral

eSaral Academic and Editorial Team

22nd June 2026

3 min read

Summary

<p>Chemical Kinetics is a high-scoring NEET Chemistry chapter focused on reaction rates, order and molecularity, first-order reactions, half-life, Arrhenius equation, and rate constants, with most NEET questions based on standard formulas, conceptual differences, and numerical problem-solving.</p>

Chemical Kinetics - NEET Previous Year Questions with Complete Solutions

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Chemical Kinetics in NEET: Weightage and Key Topics

How Many Questions Come from Chemical Kinetics in NEET?

Chemical Kinetics is one of the most consistently tested chapters in NEET Chemistry, contributing 2–3 questions almost every year. It rewards students who understand both the conceptual distinctions (order vs molecularity, rate law vs stoichiometry) and the numerical applications (half-life, Arrhenius calculations).

Year	Questions from Chemical Kinetics	Topics Tested
NEET 2024	2	First-order half-life, Arrhenius equation
NEET 2023	2	Rate law, order of reaction determination
NEET 2022	3	Integrated rate equation, activation energy, molecularity
NEET 2021	2	Half-life, rate constant units
NEET 2020	2	Arrhenius equation, pseudo-first-order reaction
NEET 2019	3	Rate of reaction, order determination, t½
NEET 2018	2	First-order kinetics, activation energy

Which Topics Are Most Frequently Tested?

Based on NEET papers from 2010 to 2024, the six highest-frequency topics in Chemical Kinetics are:

First order reaction — integrated rate equation and half-life (t½ = 0.693/k)
Order of reaction determination from experimental rate data
Arrhenius equation — calculating activation energy or rate constant at different temperatures
Units of rate constant for zero, first, and second order reactions
Molecularity vs order — conceptual distinction
Pseudo first-order reactions — examples and conditions

💡 Expert Tip by eSaral Faculty: At least one NEET question every year is directly solvable using t½ = 0.693/k for first order reactions. This is the single most tested formula in the chapter. If you know nothing else about Chemical Kinetics, know this formula — and know that for first order reactions, half-life is independent of initial concentration.

NEET PYQs: Rate of Reaction and Rate Law

Common Mistakes in Chemical Kinetics NEET Questions

Mistake 1 — Confusing Order with Molecularity

Order is experimentally determined and can be zero, fractional, or any whole number. Molecularity is a theoretical concept for elementary reactions and is always a positive whole number (1, 2, or 3). They are equal only for elementary reactions.

Mistake 2 — Using Wrong Units for Rate Constant

Units of k depend entirely on reaction order:

Zero order: mol L⁻¹ s⁻¹
First order: s⁻¹
Second order: L mol⁻¹ s⁻¹

Memorise these. NEET asks unit-identification questions directly.

Mistake 3 — Assuming Half-Life Depends on Concentration for First Order

For first order reactions, t½ = 0.693/k — completely independent of initial concentration. Only for zero and second order reactions does half-life depend on [A]₀. This distinction is tested conceptually in NEET almost every year.

The correct form is: log(k₂/k₁) = (Ea/2.303R)(1/T₁ – 1/T₂)

Note the order: 1/T₁ – 1/T₂ where T₁ < T₂. Students who reverse this get a negative Ea — which is physically impossible for most reactions.

Mistake	How to Avoid
Confusing order with molecularity	Order = experimental; molecularity = theoretical, whole number only
Wrong rate constant units	Zero = mol/L/s; First = 1/s; Second = L/mol/s
Thinking first order t½ depends on [A]₀	First order t½ = 0.693/k — always constant
Reversing T₁ and T₂ in Arrhenius	Use 1/T₁ – 1/T₂ where T₁ is lower temperature
Mixing up rate law with stoichiometry	Rate law coefficients come from experiment, not balanced equation

Frequently Asked Questions

How many questions come from Chemical Kinetics in NEET every year?

Chemical Kinetics contributes 2–3 questions in NEET Chemistry almost every year, making it one of the most reliably tested chapters. Topics appearing most consistently include first order half-life, order of reaction determination from data, Arrhenius equation calculations, units of rate constant, and pseudo first-order reactions.

What is the weightage of Chemical Kinetics in NEET Chemistry?

Chemical Kinetics carries approximately 5–8% weightage in NEET Chemistry, contributing 2–3 questions worth 8–12 marks. Along with Electrochemistry and Liquid Solutions, it is one of the three most consistently tested chapters from Class 12 Chemistry in NEET every year.

What is the half-life of a first order reaction?

The half-life of a first order reaction is t½ = 0.693/k, where k is the rate constant. A key feature of first order reactions is that half-life is completely independent of initial concentration — it remains constant throughout the reaction. This is one of the most tested facts in Chemical Kinetics NEET questions.

What is the difference between order and molecularity of a reaction?

Order of reaction is determined experimentally from the rate law — it can be zero, fractional, or any whole number, and applies to both elementary and complex reactions. Molecularity is a theoretical concept that applies only to elementary reactions — it is always a positive whole number (1, 2, or 3) representing the number of species colliding in a single step.

How do I use the Arrhenius equation in NEET numericals?

For NEET, use the log form: log(k₂/k₁) = (Ea/2.303R) × (1/T₁ – 1/T₂), where T₁ is the lower temperature and T₂ is the higher temperature. Substitute R = 8.314 J/mol·K, temperatures in Kelvin, and solve for Ea or k₂. Always check that Ea comes out positive — if it is negative, you have reversed T₁ and T₂.

Team eSaral

eSaral Academic and Editorial Team

SL Arora Physics Class 12 index — complete chapter list for Volume 1 & 2, mapped to NCERT solutions for board, JEE Main, and NEET preparation.

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Chemical Kinetics - NEET Previous Year Questions with Complete Solutions

Summary

Chemical Kinetics in NEET: Weightage and Key Topics

How Many Questions Come from Chemical Kinetics in NEET?

Which Topics Are Most Frequently Tested?

NEET PYQs: Rate of Reaction and Rate Law

Common Mistakes in Chemical Kinetics NEET Questions

Mistake 1 — Confusing Order with Molecularity

Mistake 2 — Using Wrong Units for Rate Constant

Mistake 3 — Assuming Half-Life Depends on Concentration for First Order

Mistake 4 — Wrong Sign in Arrhenius Log Formula

Frequently Asked Questions

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