NCERT Solutions for Class 11 Physics Chapter 13 – Kinetic Theory

NCERT Solutions for Class 11 Physics Chapter 13 Kinetic Theory are one of the highly recommended study materials to refer to while you are preparing for your Class 11 exams. The NCERT solutions will not only help you understand the chapter thoroughly and you will be able to answer all the questions properly in the exams.

This chapter on Kinetic Theory describes the behaviour of various gases. The main topics of the chapter include Temperature and Pressure, Specific Heat Capacities, the Relation between Molecular Parameters and Measurable Aspects of Gases like Viscosity, Conduction and Diffusion. There are 14 questions at the end of the chapter in the NCERT book.

CBSE Class 11 Physics Chapter 13 Kinetic Theory is an important chapter in the Physics textbook as it introduces you to the basic concepts which can be asked in any of the entrance examinations like JEE and NEET. Therefore, we have created the NCERT solutions with clear explanations along with diagrams so that you can understand the topics without any hassle.

Important Points for NCERT Class 11 Physics Chapter 13 – Kinetic Theory

Molecular Nature of Matter

The section of the NCERT Solutions for Class 11 Physics Chapter 13 explains the different molecules of matter and how they can be observed. The different attractive and repulsive interatomic forces that are in play have been explained and how the gas is full of activity. This section further talks about the Atomic Theory and how atoms are subdivided into Electrons, Protons and Neutrons.

Mean Free Path

The average distance a molecule can travel without colliding is called the mean free path.

Behaviour of Gases

This section of the NCERT chapter talks about the different properties of gases which are easier to understand than that of solids and liquids. The simple relation between the temperature, pressure and volume of gases is given hereby:


where T is the temperature in Kelvin and K is the constant for the given sample but varies with the volume of the gas.

Boyle’s Law

It is an experimental gas law that describes how the pressure of a gas tends to increase as the volume of the container decreases. Mathematically, Boyle’s Law can be stated as;

i.e, pressure is inversely proportional to the volume, where P is the pressure of the gas and V is the volume of the gas and k is constant.

The hypothesis is given by Avogadro which says that at the same temperature and pressure, equal volumes of all the gases have the same number of molecules.

Kinetic Theory of Ideal Gas

This topic of the chapter talks about the kinetic theory of gases and what happens when the molecules in the gases collide with each other. The interaction between the molecules is negligible and it is assumed that they move freely in the straight lines according to Newton’s First Law.

The pressure of a fluid is explained which is not only exerted on the wall but also exists everywhere in a fluid. Any layer of gas inside the volume of a container is in equilibrium because the pressure is the same on both the sides of the layer.

Law of Equipartition of Energy

The degrees of freedom of movement of molecules in a plane, a straight line and space is discussed in this section. A derivation for the average value of energy for gas at the Thermal Equilibrium at a specific temperature has also been derived in this section of the chapter. The Law of Equipartition of Energy states that in thermal equilibrium, the total energy of the molecule is divided equally among all degrees of freedom of motion.

Exercise-wise discussion of NCERT Solutions for Class 11 Physics Chapter 13 

The NCERT Physics Class 11 Chapter 13 consists of one exercise which consists of 10 questions and an additional exercise with 4 extra questions for practice. All are numerical based questions for practising.

The first few questions of the NCERT exercise of the chapter are about finding the volume of the gas. Then, in the next few questions, you will be required to find the molecular mass of gases. 

The questions mentioned in the additional exercise are of advanced level. You need to find the size of atoms of the gases. You will also practice the consequence of the kinetic theory, the law of atmospheres and the Archimed’s principle in these questions. 

Benefits of NCERT Solutions for Class 11 Physics Chapter 13 by Instasolv 

NCERT Solutions for Class 11 Physics Chapter 13 Kinetic Theory are prepared by our subject matter experts with utmost dedication and quality. They are well aware of the CBSE exam pattern and have created the answers accordingly. All the concepts have been explained with the help of examples and graphs so that you can learn the concepts more effectively. These solutions will not only help you to score well in CBSE exams but will also equally prove useful in clearing all your concepts for any future competitive exams.