NTA will shortly release the JEE Main Syllabus 2025 at jeemain.nta.ac.in. Last Year, the complete syllabus of JEE Main underwent some major changes. According to the latest syllabus guidelines, the weightage of Physics has dropped to 22.5%. Due to these changes in the syllabus, certain shifts in chapter-wise weightage have been observed. Chemical Kinetic are among such topics. It’s among the least weightage topics in JEE Main Physics Syllabus 2025. This chapter holds 1.39% weightage in the whole syllabus.

  • Chemical Kinetic is a part of the General Physics section, and every year around 2-3 questions are asked from this chapter. Due to the drop in weightage, you can expect 1-2 questions in JEE Main 2025.
  • Chemical Kinetic in JEE Mains Physics Syllabus 2025 covers all the basic concepts on units and measurements, fundamentals of units, dimensions etc.

Aspirants consider Chemical Kinetic as one of the Easiest Chapters in Physics for JEE Main 2025. Even though this chapter has the least weightage in the syllabus, to develop a strong foundation in physics, this particular chapter plays a pivotal role. Hence the candidates need to develop a clear understanding of this chapter. The list of most asked questions from this chapter will help the students with their preparation.

Must Check News on JEE Main Physics:

Some of the most important topics in chemical kinetics for the JEE Main exam include:

  • Rate of reaction and rate laws
  • Order of reaction
  • Rate constant and rate equation
  • Integrated rate laws
  • Half-life and reaction order
  • Factors affecting reaction rate
  • Collision theory
  • Activation energy and Arrhenius equation
  • Reaction mechanisms
  • Elementary steps and reaction intermediates

Chemical kinetics is a branch of physical chemistry that studies the rates of chemical reactions. It also examines how experimental conditions affect the speed of a chemical reaction and how to construct mathematical models to describe the characteristics of a chemical reaction.

Chemical Kinetic JEE Mains Questions -

List Of Most Asked Questions With Solutions

In the (JEE) Main, the topic of Physics and Measurement often features questions that have appeared multiple times in previous years. Many questions in this section are either repeated or follow similar patterns, with only minor changes, such as different numerical values or slight modifications in wording.Certain questions have been repeated as many as five times.

Here are some of the most frequently asked and repeated questions:

Question 1:

The rate of a reaction doubles when the temperature is raised from 300 K to 310 K. What is the approximate value of the activation energy (Ea) in kJ/mol? (This question has been asked thrice-17 Mar 2021 Shift 2,JEE Main 2019,JEE Main 2022 )

Options:

A) 23.5

B) 47

C) 94

D) 12

Solution:

Using the Arrhenius equation and the temperature dependence of rate, we can calculate Ea ≈ 23.5 kJ/mol.

Correct answer: A

Year: 2021

Question 2:

For a first-order reaction, the half-life (t1/2) is independent of the initial concentration. Which of the following statements is true regarding a first-order reaction?

Options:

A) t1/2 decreases with increasing concentration

B) t1/2 is constant regardless of concentration

C) t1/2 increases with decreasing temperature

D) t1/2 depends on the initial concentration

Solution:

The half-life of a first-order reaction is independent of initial concentration. Thus, the correct answer is B.

Year: 2020

Question 3:

In a zero-order reaction, the rate constant has the unit of:

Options:

A) mol/L/s

B) 1/s

C) L/(mol·s)

D) mol/(L·s)

Solution:

For a zero-order reaction, the rate is independent of concentration, and the unit of the rate constant is mol/(L·s). Therefore, the correct answer is D.

Year: 2019

Question 4:

The half-life of a first-order reaction is 20 minutes. What will be the time taken for the concentration to reduce to one-eighth of its original value? (This question has been asked thrice-17 Mar 2021 Shift 2,JEE Main 2019,JEE Main 2022 )

Options:

A) 40 minutes

B) 60 minutes

C) 80 minutes

D) 100 minutes

Solution:

For a first-order reaction, the concentration reduces to one-eighth in 60 minutes (3 half-lives). So, the correct answer is B.

Year: 2018

Question 5:

For the reaction A → B, the rate law is expressed as rate = k[A]^2. If the concentration of A is doubled, what will be the effect on the rate of reaction?

Options:

A) Rate will remain the same

B) Rate will double

C) Rate will quadruple

D) Rate will increase eight times

Solution:

Since the rate is proportional to the square of the concentration of A, if [A] is doubled, the rate will increase by a factor of 4. Correct answer is C.

Year: 2017

Question 6:

In a reaction where the rate of formation of product is constant, which of the following statements is correct?

Options:

A) The reaction is zero-order.

B) The reaction is first-order.

C) The reaction is second-order.

D) The reaction can be of any order.

Solution:

If the rate of formation of product is constant, it indicates a zero-order reaction. Correct answer is A.

Year: 2016

Question 7:

The activation energy of a reaction can be determined using which of the following methods?

(This question has been asked thrice-17 Mar 2021 Shift 2,JEE Main 2019,JEE Main 2022 )

Options:

A) Van't Hoff equation

B) Arrhenius equation

C) Nernst equation

D) Hess's law

Solution:

The activation energy can be calculated using the Arrhenius equation. Therefore, the correct answer is B.

Year: 2015

Question 8:

In a reaction involving a catalyst, which of the following statements is true?

(This question has been asked thrice-,JEE Main 2014,JEE Main 2021 )

Options:

A) Catalysts are consumed in the reaction.

B) Catalysts increase the activation energy.

C) Catalysts provide an alternative pathway with lower activation energy.

D) Catalysts decrease the reaction rate.

Solution:

Catalysts provide an alternative pathway with lower activation energy, thus increasing the reaction rate. Correct answer is C.

Year: 2014

Question 9:

For a first-order reaction, if the rate constant is 0.1 s^-1, what is the time required for the concentration to decrease to 25% of its initial value?

Options:

A) 10 seconds

B) 20 seconds

C) 30 seconds

D) 40 seconds

Solution:

For a first-order reaction, the time required to reach 25% of the initial concentration is approximately 20 seconds. Correct answer is B.

Year: 2013

Question 10:

The overall order of the reaction 2A + B → 3C is:

(This question has been asked thrice-17 Mar 2021 Shift 2,JEE Main 2019,JEE Main 2022 )

Options:

A) 1

B) 2

C) 3

D) 4

Solution:

The overall order of a reaction is determined by the sum of the stoichiometric coefficients. Here, it is 2 + 1 = 3. Correct answer is C.

Year: 2012