Chemical Kinetics Class 12 Chemistry MCQs

Chemical Kinetics is an important chapter in Class 12 Chemistry that helps students understand the rates of chemical reactions and the factors that affect them. It plays a vital role in explaining how fast or slow a reaction happens, making it crucial for students preparing for board exams, competitive exams like JEE and NEET, and even higher studies in chemistry. To make learning this topic more effective, practicing multiple-choice questions (MCQs) can be extremely helpful.

MCQs on Chemical Kinetics are designed to test your understanding of key concepts, such as reaction rates, rate laws, order of reactions, molecularity, and the effect of temperature and catalysts. These questions often require you to apply formulas, analyze graphs, and solve problems based on real-world scenarios. By practicing MCQs, you can improve your ability to think critically and solve problems quickly, which is essential for exams.

This chapter covers several interesting topics, like the difference between average and instantaneous reaction rates, the Arrhenius equation, and how activation energy influences reactions. It also explains first-order and second-order reactions, along with their graphs and equations. Questions in this section often include numerical problems, theoretical concepts, and practical applications.

Practicing Chemical Kinetics MCQs will not only help you strengthen your basics but also boost your confidence in solving exam-related problems. These questions are often framed to challenge your understanding and encourage logical thinking. For example, you might encounter questions where you need to determine the rate constant, calculate half-life, or analyze the effect of temperature on reaction speed.

In this set of MCQs, we have carefully selected questions that cover all important concepts of Chemical Kinetics, ensuring a balanced mix of theory and numerical problems. Whether you are revising for exams or testing your knowledge, these questions will serve as a valuable resource.

By solving these MCQs, you can identify your weak areas, improve your accuracy, and gain a better understanding of the chapter. Remember, consistent practice and a clear understanding of concepts are the keys to mastering Chemical Kinetics and scoring well in your exams. So, get started and make the most of this opportunity to excel in your Chemistry studies!

Class 12 Chemical Kinetics MCQs

Ques 1. The expression dt−d[X]​ in a rate equation refers to:

a) Concentration of the reactant

b) Decrease in reactant concentration over time

c) Velocity constant of the reaction

d) None of the above

Answer: b) Decrease in reactant concentration over time

Ques 2. In the reaction $A+2B\to C$, where the rate isR=[A][B]², what is the reaction order?

a) 2

b) 3

c) 4

d) 5

Answer: b) 3

Do Check: Important Questions for Class 12 Chemistry Chapter 4 Chemical Kinetics

Ques 3. For a zero-order reaction, the rate is independent of:

a) Temperature

b) Reactant concentration

c) Catalyst presence

d) Volume of the reaction vessel

Answer: b) Reactant concentration

Ques 4. A catalyst increases the reaction rate by:

a) Lowering the activation energy

b) Raising the enthalpy

c) Increasing the internal energy

d) Decreasing the temperature

Answer: a) Lowering the activation energy

Ques 5. The half-life of a first-order reaction:

a) Increases with temperature

b) Decreases with temperature

c) Remains constant regardless of temperature

d) Depends on the catalyst

Answer: b) Decreases with temperature

Ques 6. The rate of disappearance of reactant Q in the reaction $P+Q\to R+S$ is given as:

a) Equal to the rate of appearance of S

b) Equal to twice the rate of appearance of R

c) Equal to half the rate of appearance of R

d) Independent of the rate of reaction

Answer: c) Equal to half the rate of appearance of R

Ques 7. The time taken for 30% decomposition of a first-order reaction is 40 minutes. What is its half-life (t_1/2​)?

a) 77.7 minutes

b) 52.5 minutes

c) 30 minutes

d) 100 minutes

Answer: a) 77.7 minutes

Ques 8. What is the effect of increasing temperature on a Maxwell-Boltzmann distribution graph?

a) Curve shifts forward and downward

b) Curve shifts backward and upward

c) Curve remains unchanged

d) Curve shifts forward and upward

Answer: a) Curve shifts forward and downward

Do Check: NCERT Solutions for Class 12 Chemistry Chapter 4 Chemical Kinetics

Ques 9. In a reaction, the driving force is:

a) Energy absorbed

b) Free energy change

c) Temperature change

d) Activation energy

Answer: b) Free energy change

Ques 10. What is the rate of reaction if the concentration of

 

a) 2×10−4Ms⁻¹

b) 4×10−2Ms⁻¹

c) 2×10−2Ms⁻¹

d) 1×10−2Ms⁻¹

Answer: a) 2×10−4Ms⁻¹

Ques 11. For the reaction

$2X → Y$

2X→Y, how much time is required for 87.5% completion if the half-life is 30 minutes?

a) 90 minutes

b) 120 minutes

c) 60 minutes

d) 30 minutes

Answer: a) 90 minutes

Ques 12. Which of the following defines the rate constant for a reaction?

a) The rate when reactant concentration is 1 M

b) The rate when reactant concentration is zero

c) The ratio of rate to product concentration

d) None of the above

Answer: a) The rate when reactant concentration is 1 M

Ques 13. The plot of concentration vs. time for a first-order reaction is:

a) Linear

b) Exponential

c) Parabolic

d) Hyperbolic

Answer: b) Exponential

Ques 14. The study of reaction kinetics involves:

a) Rate of reaction

b) Reaction mechanism

c) Factors affecting the reaction rate

d) All of the above

Answer: d) All of the above

Ques 15. In a reaction $A+2B\to 2C$, the rate law is R=k[A]₂[B]. What is the correct order?

a) 1

b) 3

c) 2

d) 5

Answer: b) 3

Ques 16. Which of these influences reaction rate in a solution?

a) Temperature

b) Catalyst

c) Activation energy

d) All of the above

Answer: d) All of the above

Do Check: NCERT Exemplar Solutions for Class 12 Chemistry Chapter 4 – Chemical Kinetics

Ques 17. The reaction

$2NO + O_2 → 2NO_2$

2NO+O₂​→2NO_2​ follows a rate law R=k[NO]₂[O₂​]. What is the molecularity?

a) 1

b) 2

c) 3

d) 4

Answer: c) 3

Ques 18. What happens to the rate constant if the temperature is increased?

a) Decreases

b) Increases

c) Remains constant

d) Doubles

Answer: b) Increases

Ques 19. A reaction is zero-order. Its rate depends on:

a) Reactant concentration

b) Product concentration

c) Catalyst only

d) None of the above

Answer: d) None of the above

Ques 20. The temperature coefficient is expressed as:

a)

$\frac{k_{T+10}}{k_T}$

​​

b)

$\frac{k_{T+20}}{k_T}$

​​

c)

$\frac{k_{T+30}}{k_T}$

​​

d)

$\frac{k_{T+40}}{k_T}$

​​

Answer: a)

$\frac{k_{T+10}}{k_T}$

​​

Ques 21. Which method is best suited for simple reactions?

a) Integration method

b) Half-life method

c) Graphical method

d) Isolation method

Answer: a) Integration method

Ques 22. Heat of reaction for ethyl acetate hydrolysis is:

a) Zero

b) Less than zero

c) Greater than zero

d) None of the above

Answer: a) Zero

Ques 23. The activation energy in a reaction is:

a) The energy needed to start the reaction

b) The heat released during the reaction

c) Equal to free energy change

d) None of the above

Answer: a) The energy needed to start the reaction

Do Check: Chemistry MCQs for Class 12 with Answers Chapter 4 Chemical Kinetics

Ques 24. For a first-order reaction, if the half-life is 10 minutes, the time for 75% completion is:

a) 10 minutes

b) 20 minutes

c) 30 minutes

d) 40 minutes

Answer: b) 20 minutes

Ques 25. In reaction kinetics, which graph shows the temperature effect on reaction rates?

a) Concentration vs. time

b) Rate constant vs. temperature

c) Activation energy vs. time

d) Reaction mechanism vs. concentration

Answer: b) Rate constant vs. temperature