Chemical Kinetics - NEET Previous Year Questions with Complete Solutions

eSaral › NEET › Neet test-series›Chemical Kinetics 

🩺 Explore NEET Courses

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).

Which Topics Are Most Frequently Tested?

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

1. First order reaction — integrated rate equation and half-life (t½ = 0.693/k)
2. Order of reaction determination from experimental rate data
3. Arrhenius equation — calculating activation energy or rate constant at different temperatures
4. Units of rate constant for zero, first, and second order reactions
5. Molecularity vs order — conceptual distinction
6. 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.

Mistake 4 — Wrong Sign in Arrhenius Log Formula

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.