NEET (UG) · Chemistry, Class 12
Chemical Kinetics: NEET PYQ, 2018–2026
Chemical Kinetics (Chemistry, Class 12) has been asked 15 times in the 7 NEET papers from 2018, 2020, 2021, 2023, 2024, 2025 and 2026: about 2.1 questions a paper, 5% of all Chemistry questions. It is the 9th most-asked of 21 Chemistry chapters. NEET 2026 had 2 from it. Last checked 28 October 2026.
Questions per paper
Year by year.
| Year | Questions |
|---|---|
| 2018 | 2 |
| 2020 | 2 |
| 2021 | 2 |
| 2023 | 2 |
| 2024 | 3 |
| 2025 | 2 |
| 2026 | 2 |
From 2021 to 2024 each paper had 200 questions (a Section B with a choice); the others had 180.
Inside the chapter
Topics asked most.
- Arrhenius equation8
- Integrated rate laws and half-life6
- Rate laws1
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10 Chemical Kinetics questions to practise.
Our own questions, written in the NEET pattern and checked, each with an explanation. Pick an option to see the answer.
Q1 · Chemistry · Chemical Kinetics
What is the overall order of a reaction whose rate law is rate = k[A]^½[B]^(3/2)?
Answer: (A)
The overall order is the sum of the exponents: ½ + 3/2 = 2. So the reaction is second order overall.
Q2 · Chemistry · Chemical Kinetics
A first-order reaction is 90 % complete in 30 min. How long does it take to be 99 % complete?
Answer: (A)
t = (2.303/k) log([R]₀/[R]). For 90 %, log 10 = 1; for 99 %, log 100 = 2. So t(99 %) = 2 × t(90 %) = 60 min.
Q3 · Chemistry · Chemical Kinetics
The gas-phase reaction A(g) → 2B(g) is carried out at constant temperature in a rigid vessel, starting with pure A at a pressure of 0.40 atm. The total pressure in the vessel is 0.60 atm after 10 min and 0.70 atm after 20 min. Assuming the reaction follows simple zero-, first- or second-order kinetics in A, what is its order?
Answer: (B)
The total pressure rises because each mole of A gives two moles of B. If x is the pressure of A consumed, pA = 0.40 − x, pB = 2x and P_total = 0.40 + x. So pA = 0.80 − P_total. At 10 min, pA = 0.80 − 0.60 = 0.20 atm. At 20 min, pA = 0.80 − 0.70 = 0.10 atm. Starting from 0.40 atm, the pressure halves to 0.20 atm in 10 min and halves again to 0.10 atm in the next 10 min. A constant half-life independent of concentration is the signature of a first-order reaction. The zero-order and second-order predictions (0.80 atm and 0.667 atm) do not fit.
Q4 · Chemistry · Chemical Kinetics
Which of the following statements about the pre-exponential factor A in the Arrhenius equation k = A e^(−Ea/RT) is correct?
Answer: (A)
In the Arrhenius equation, the exponential term e^(−Ea/RT) gives the fraction of effective collisions, and A gives the collision frequency and orientation factor. Neither depends on the concentrations of the reactants, which affect only the rate. So changing concentrations leaves A unchanged, and A is treated as a constant for a given reaction at a fixed temperature.
Q5 · Chemistry · Chemical Kinetics
For a reaction A → products, a plot of log₁₀(rate) against log₁₀[A] is a straight line with slope 2. It cuts the log(rate) axis at −3.0, that is, at log₁₀[A] = 0. Concentration is in mol L⁻¹ and rate is in mol L⁻¹ s⁻¹. What is the rate of the reaction when [A] = 0.10 mol L⁻¹?
Answer: (D)
Taking logarithms of rate = k[A]ⁿ gives log(rate) = log k + n log[A]. The slope of the line is the order, n = 2. The intercept at log[A] = 0 is log k = −3, so k = 10⁻³ L mol⁻¹ s⁻¹. At [A] = 0.10 M, rate = 10⁻³ × (0.10)² = 1.0 × 10⁻⁵ mol L⁻¹ s⁻¹.
Q6 · Chemistry · Chemical Kinetics
The initial rates of the reaction A + B → products were measured at constant temperature in three experiments. Experiment 1: [A] = 0.04 M, [B] = 0.10 M, rate = 1.5 × 10⁻³ mol L⁻¹ s⁻¹. Experiment 2: [A] = 0.16 M, [B] = 0.10 M, rate = 1.2 × 10⁻² mol L⁻¹ s⁻¹. Experiment 3: [A] = 0.04 M, [B] = 0.30 M, rate = 4.5 × 10⁻³ mol L⁻¹ s⁻¹. What is the initial rate (in mol L⁻¹ s⁻¹) when [A] = 0.01 M and [B] = 0.20 M?
Answer: (A)
Compare experiments 1 and 2, where [B] is constant: [A] rises 4 times and rate rises 12 / 1.5 = 8 times, so 4^m = 8 and m = 3/2. Compare experiments 1 and 3, where [A] is constant: [B] rises 3 times and rate rises 3 times, so n = 1. The rate law is rate = k[A]^1.5[B]. For the new conditions, [A] falls to 1/4 of its Experiment 1 value, so the rate factor is (1/4)^1.5 = 1/8. [B] doubles, so the factor is 2. Rate = 1.5 × 10⁻³ × (1/8) × 2 = 3.75 × 10⁻⁴ mol L⁻¹ s⁻¹.
Q7 · Chemistry · Chemical Kinetics
A reaction has a rate constant k whose units are L mol⁻¹ s⁻¹. What is the order of this reaction?
Answer: (C)
The rate law for an nth-order reaction is rate = k[A]^n, so k = rate / [A]^n. Rate has units mol L⁻¹ s⁻¹ and concentration has units mol L⁻¹. So the units of k are (mol L⁻¹ s⁻¹)/(mol L⁻¹)^n = (mol L⁻¹)^(1−n) s⁻¹. Setting this equal to L mol⁻¹ s⁻¹ = (mol L⁻¹)⁻¹ s⁻¹ requires 1 − n = −1, so n = 2. The reaction is second order.
Q8 · Chemistry · Chemical Kinetics
The reaction NO₂(g) + CO(g) → NO(g) + CO₂(g) is believed to occur by the mechanism: Step 1 (slow): 2NO₂ → NO₃ + NO; Step 2 (fast): NO₃ + CO → NO₂ + CO₂. At constant temperature, [NO₂] is doubled and [CO] is tripled. By what factor does the rate change?
Answer: (A)
The overall rate is controlled by the slowest (rate-determining) step. Step 1 is an elementary bimolecular step involving two NO₂ molecules, so rate = k[NO₂]². CO enters only in the fast second step and is zero order. Doubling [NO₂] gives 2² = 4, and tripling [CO] has no effect, so the rate rises by a factor of 4.
Q9 · Chemistry · Chemical Kinetics
A first-order reaction has a half-life of 6.93 min. What is the rate of the reaction at the instant when the concentration of the reactant is 0.5 mol L⁻¹? (ln 2 = 0.693)
Answer: (A)
For a first-order reaction, k = 0.693 / t½ = 0.693 / 6.93 = 0.1 min⁻¹. Rate = k[R] = 0.1 × 0.5 = 0.05 mol L⁻¹ min⁻¹.
Q10 · Chemistry · Chemical Kinetics
A first-order reaction has a rate constant of 1.5 × 10⁻² s⁻¹. What is its rate constant expressed in min⁻¹?
Answer: (A)
The unit of a first-order rate constant is time⁻¹. Converting from per second to per minute means one unit of time⁻¹ in s⁻¹ corresponds to 60 units in min⁻¹. So k = 1.5 × 10⁻² s⁻¹ × 60 s/min = 0.9 min⁻¹. The numerical value of k rises when the time unit is made larger.
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All 15 real NEET questions from Chemical Kinetics.
The questions from the actual papers, with the official answer and an explanation for each — chapter by chapter, or as full timed papers.
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About Chemical Kinetics in NEET.
How many questions come from Chemical Kinetics in NEET?
Chemical Kinetics (Chemistry, Class 12) has been asked 15 times in the 7 NEET papers from 2018, 2020, 2021, 2023, 2024, 2025 and 2026: about 2.1 questions a paper, 5% of all Chemistry questions. It is the 9th most-asked of 21 Chemistry chapters. NEET 2026 had 2 from it.
Which topics of Chemical Kinetics are asked most in NEET?
Arrhenius equation (8), Integrated rate laws and half-life (6), Rate laws (1), counted over the papers from 2018–2026.
Is Chemical Kinetics important for NEET 2027?
It is in the syllabus in force, so it can be asked. By past papers it ranks 9 of 21 in Chemistry; use that to decide how much time it gets, not whether to study it.
Where can I solve Chemical Kinetics NEET previous year questions?
On Nikaalle, free: sign up and practise every past NEET question from Chemical Kinetics with an explanation for each, or sit the full papers timed. The ten questions on this page are our own, written in the same pattern.
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