Chemical Kinetics Practice Questions

Class 12 · Chemistry · 2282 free MCQs with instant results and detailed explanations.

2282

Total

726

Easy

1112

Medium

444

Hard

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Topics in Chemical Kinetics

Arrhenius Equation 580

Order of Reaction 533

Collision Theory 617

Rate of Reaction 552

Sample Questions from Chemical Kinetics

Here are 10 sample questions. Start a quiz to get randomized questions with scoring.

Easy

What is the unit of rate constant for a first-order reaction?

A. s⁻¹

B. M⁻¹ s⁻¹

C. M s⁻¹

D. M² s⁻¹

Show Answer & Explanation

Correct Answer: A

For a first-order reaction, the rate constant has units of s⁻¹, indicating the change in concentration per unit time.

Easy

Which factor does NOT affect the rate of a chemical reaction?

A. Concentration

B. Temperature

C. Nature of reactants

D. Color of reactants

Show Answer & Explanation

Correct Answer: D

The color of reactants does not influence the rate of reaction, while concentration, temperature, and nature of reactants do.

Easy

For a reaction A → B, if the concentration of A is doubled, how does the rate change in a first-order reaction?

A. Doubles

B. Quadruples

C. Remains the same

D. Halves

Show Answer & Explanation

Correct Answer: A

In a first-order reaction, the rate is directly proportional to the concentration of reactant, so doubling A doubles the rate.

Medium

Which of the following factors does NOT affect the rate of a chemical reaction?

A. Concentration of reactants

B. Presence of a catalyst

C. Nature of reactants

D. Color of the reactants

Show Answer & Explanation

Correct Answer: D

The color does not influence the chemical reaction rate, while concentration, catalyst, and nature of reactants do.

Medium

In a first-order reaction, if the half-life is 30 minutes, what will be the half-life if the concentration is tripled?

A. 10 minutes

B. 30 minutes

C. 90 minutes

D. None of the above

Show Answer & Explanation

Correct Answer: B

In a first-order reaction, half-life is independent of concentration. Hence, it remains 30 minutes.

Medium

The unit of the rate constant (k) for a zero-order reaction is:

A. mol/L·s

B. s⁻¹

C. mol/L

D. mol/L·s²

Show Answer & Explanation

Correct Answer: A

For a zero-order reaction, the rate is equal to k, and its unit is mol/L·s.

Medium

Which of the following statements is true about catalysts?

A. They increase the activation energy.

B. They are consumed in the reaction.

C. They alter the equilibrium constant.

D. They lower the activation energy.

Show Answer & Explanation

Correct Answer: D

Catalysts lower the activation energy, thus increasing the reaction rate, and are not consumed.

Hard

What is the overall order of the reaction if the rate law is rate = k[A]^2[B]^1?

A. 3

B. 2

C. 1

D. 0

Show Answer & Explanation

Correct Answer: A

The overall order is the sum of the powers of the concentration terms in the rate law, which is 2+1 = 3.

Hard

In a first-order reaction, how does the half-life depend on the initial concentration?

A. Directly proportional

B. Inversely proportional

C. Independent

D. Exponential

Show Answer & Explanation

Correct Answer: C

For a first-order reaction, the half-life is constant and does not depend on the initial concentration.

Q10

Hard

A reaction has an activation energy of 75 kJ/mol. How will the rate change if the temperature increases from 298 K to 318 K?

A. Rate doubles

B. Rate increases 4 times

C. Rate increases 8 times

D. Rate remains unchanged

Show Answer & Explanation

Correct Answer: B

The Arrhenius equation shows that a small increase in temperature can significantly increase the reaction rate; a rule of thumb is that the rate can roughly quadruple for every 10 K increase.

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Chemical Kinetics — Class 12 Chemistry Practice Questions Online

This page contains 2282 practice MCQs for the chapter Chemical Kinetics in Class 12 Chemistry. The questions are organized by difficulty — 726 easy, 1112 medium, 444 hard — so you can choose the right level for your preparation.

Every question includes a detailed explanation to help you understand the concept, not just memorize answers. Take a timed quiz to simulate exam conditions, or practice at your own pace with no time limit. This chapter covers 4 topics, giving you comprehensive coverage of the entire chapter.