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Chemical Kinetics CBSE Class 12 MCQ & Practice Questions

Practice Chemical Kinetics MCQs for CBSE Class 12 Chemistry with answers, explanations, chapter revision and related ChemNexa mock tests.

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Chemical Kinetics Revision Guide for CBSE Class 12 Chemistry

Chemical Kinetics explains how fast chemical reactions occur and how rate changes with concentration, temperature and catalysts. Exam questions often combine definitions with graphs, integrated rate equations and half-life relationships.

For CBSE Class 12 Chemistry, focus on distinguishing rate law from stoichiometric coefficients, identifying reaction order from experimental data, using integrated equations correctly and interpreting the Arrhenius equation.

Important Topics

  • Rate of reaction and rate law
  • Order and molecularity
  • Integrated rate equations
  • Half-life of zero and first order reactions
  • Arrhenius equation and activation energy
  • Catalysis and temperature dependence

Important Formulae & Relationships

  • Rate = k[A]^m[B]^n
  • First order: ln([A]0/[A]) = kt
  • First-order half-life: t1/2 = 0.693/k
  • Arrhenius: k = Ae^(−Ea/RT)
  • ln(k2/k1) = −Ea/R (1/T2 − 1/T1)

Use formulas only after checking the required units, sign convention and assumptions for the question.

What to practise in Chemical Kinetics

Concept Revision

Revise definitions, principles, equations, trends and core ideas from Chemical Kinetics before attempting MCQs.

Exam-style MCQs

Use chapter-focused multiple-choice practice to improve accuracy, recall and application for CBSE Class 12 Chemistry.

Performance Practice

Attempt ChemNexa tests, review results and return to weak areas for another round of targeted revision.

Top 20 Chemical Kinetics MCQs with Answers

These public questions are selected from the exact Chemical Kinetics chapter, screened for topic relevance and deduplicated so repeated versions of the same MCQ are not shown publicly. Use them for quick revision, then sign in to attempt the complete test experience with more questions, results and performance review.

CBSE Class 12 Chemistry · Chemical Kinetics · Very Very Hard

1. A catalyst increases reaction rate by

  • A. Increasing ΔH
  • B. Lowering activation energy
  • C. Changing equilibrium constant
  • D. Increasing product stability only
Answer: B
Explanation: A catalyst provides an alternative pathway with lower activation energy.

CBSE Class 12 Chemistry · Chemical Kinetics · Very Very Hard

2. The unit of rate constant for a first-order reaction is

  • A. s⁻¹
  • B. mol L⁻¹ s⁻¹
  • C. L mol⁻¹ s⁻¹
  • D. L² mol⁻² s⁻¹
Answer: A
Explanation: For first order, k has dimension time⁻¹.

CBSE Class 12 Chemistry · Chemical Kinetics · Very Very Hard

3. The unit of rate constant for a second-order reaction is

  • A. s⁻¹
  • B. L mol⁻¹ s⁻¹
  • C. mol L⁻¹ s⁻¹
  • D. L² mol⁻²
Answer: B
Explanation: For second order, k has units concentration⁻¹ time⁻¹.

CBSE Class 12 Chemistry · Chemical Kinetics · Very Very Hard

4. For a first-order reaction, the integrated equation is

  • A. ln([A]₀/[A]) = kt
  • B. [A] = [A]₀ − kt
  • C. 1/[A] = 1/[A]₀ + kt
  • D. [A]² = [A]₀² − kt
Answer: A
Explanation: The first-order integrated law is ln([A]₀/[A]) = kt.

CBSE Class 12 Chemistry · Chemical Kinetics · Very Very Hard

5. The rate of a chemical reaction is defined as

  • A. Change in concentration per unit time
  • B. Change in temperature per unit mass
  • C. Pressure divided by volume
  • D. Moles multiplied by time
Answer: A
Explanation: Reaction rate is the change in concentration of reactant or product per unit time.

CBSE Class 12 Chemistry · Chemical Kinetics · Very Very Hard

6. For a reaction A → products, the rate law is rate = k

  • A. Zero
  • B. One
  • C. Two
  • D. Three
Answer: C
Explanation: The exponent of concentration in the rate law is 2.

CBSE Class 12 Chemistry · Chemical Kinetics · Very Very Hard

7. Which statement about reaction order is correct?

  • A. It is always an integer
  • B. It is determined experimentally
  • C. It always equals stoichiometric coefficient
  • D. It can never be zero
Answer: B
Explanation: Reaction order is obtained experimentally and may be zero, fractional, or integral.

CBSE Class 12 Chemistry · Chemical Kinetics · Very Very Hard

8. For a zero-order reaction, concentration varies with time as

  • A. [A] = [A]₀e⁻ᵏᵗ
  • B. [A] = [A]₀ − kt
  • C. 1/[A] = 1/[A]₀ + kt
  • D. ln[A] = ln[A]₀ + kt
Answer: B
Explanation: The integrated zero-order law is [A] = [A]₀ − kt.

CBSE Class 12 Chemistry · Chemical Kinetics · Very Very Hard

9. The half-life of a first-order reaction is

  • A. Directly proportional to initial concentration
  • B. Independent of initial concentration
  • C. Inversely proportional to initial concentration
  • D. Zero
Answer: B
Explanation: t₁/₂ = 0.693/k, independent of [A]₀.

CBSE Class 12 Chemistry · Chemical Kinetics · Very Very Hard

10. The half-life of a zero-order reaction is

  • A. 0.693/k
  • B. [A]₀/2k
  • C. 1/k[A]₀
  • D. 2k/[A]₀
Answer: B
Explanation: For zero order, t₁/₂ = [A]₀/(2k).

CBSE Class 12 Chemistry · Chemical Kinetics · Very Very Hard

11. A catalyst changes the equilibrium constant of a reversible reaction

  • A. Always increases it
  • B. Always decreases it
  • C. Does not change it
  • D. Makes it zero
Answer: C
Explanation: A catalyst speeds both forward and reverse reactions equally without changing K.

CBSE Class 12 Chemistry · Chemical Kinetics · Very Very Hard

12. A pseudo-first-order reaction is one in which

  • A. True order is zero
  • B. One reactant is present in large excess
  • C. All reactants have equal concentration
  • D. The catalyst is absent
Answer: B
Explanation: The concentration of the excess reactant remains nearly constant and is absorbed into k.

CBSE Class 12 Chemistry · Chemical Kinetics · Very Very Hard

13. Hydrolysis of an ester in excess water is commonly treated as

  • A. Zero order
  • B. Pseudo-first order
  • C. Second order only
  • D. Third order
Answer: B
Explanation: Water concentration is effectively constant, giving pseudo-first-order kinetics.

CBSE Class 12 Chemistry · Chemical Kinetics · Very Very Hard

14. The unit of reaction rate is commonly

  • A. mol L⁻¹ s⁻¹
  • B. mol² L⁻²
  • C. s mol⁻¹
  • D. L mol⁻¹
Answer: A
Explanation: Rate has concentration divided by time units.

CBSE Class 12 Chemistry · Chemical Kinetics · Very Very Hard

15. The overall order of rate = k

  • A. 1
  • B. 2
  • C. 3
  • D. 4
Answer: C
Explanation: Overall order is the sum of exponents: 2 + 1 = 3.

CBSE Class 12 Chemistry · Chemical Kinetics · Very Very Hard

16. Molecularity is defined only for

  • A. Overall complex reactions
  • B. Elementary steps
  • C. Equilibrium mixtures
  • D. Photochemical reactions only
Answer: B
Explanation: Molecularity refers to the number of reacting species in an elementary step.

CBSE Class 12 Chemistry · Chemical Kinetics · Very Very Hard

17. For a first-order reaction, a plot of ln

  • A. A straight line with slope +k
  • B. A straight line with slope −k
  • C. A parabola
  • D. Horizontal
Answer: B
Explanation: ln[A] = ln[A]₀ − kt, so slope = −k.

CBSE Class 12 Chemistry · Chemical Kinetics · Very Very Hard

18. If doubling concentration does not change the rate, the order is

  • A. Zero
  • B. One
  • C. Two
  • D. Half
Answer: A
Explanation: Rate independent of concentration indicates zero order.

CBSE Class 12 Chemistry · Chemical Kinetics · Very Very Hard

19. According to Arrhenius equation, k is

  • A. Ae⁻ᴱᵃ/ᴿᵀ
  • B. A + Ea/RT
  • C. Ea/ART
  • D. RT/Ae
Answer: A
Explanation: The Arrhenius equation is k = Ae^(-Ea/RT).

CBSE Class 12 Chemistry · Chemical Kinetics · Very Very Hard

20. A plot of ln k versus 1/T has slope

  • A. +Ea/R
  • B. −Ea/R
  • C. +R/Ea
  • D. −R/Ea
Answer: B
Explanation: From ln k = ln A − Ea/(RT), slope = −Ea/R.

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Chemical Kinetics Practice Tests

Chemical Kinetics Frequently Asked Questions

What is the most important distinction in Chemical Kinetics?

Do not confuse reaction order with stoichiometric coefficients. Reaction order is determined from the experimentally observed rate law.

Which kinetics formulas should I memorise?

Know the integrated zero- and first-order equations, half-life relations and the Arrhenius equation, but also understand the units and conditions under which each is valid.

How can I reduce mistakes in kinetics numericals?

Write the order first, choose the matching integrated equation, keep units consistent and check whether logarithms are natural or base-10.

Continue with another chapter to build connected concepts and strengthen your overall Chemistry preparation.

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