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NCERT Solutions Class 11 Physics Chapter 12 Kinetic Theory - PDF Download

Class 11

The NCERT Solutions for Class 11 chapter 12 Kinetic Theory are a crucial resource that help students score good marks in the exams and the entrance examination for graduate courses. Chapter 12, Kinetic Theory, is a key Chapter as it introduces learners to the basic concepts which will be often asked in the entrance examination. NCERT Solutions contain detailed explanations and accurate answers to provide you with a solid understanding of concepts to clear your exams.

Chapter 12 contains a big portion of the Syllabus 2023-24. It has some crucial concepts like atomic theory, gas laws, Boltzmann constant, Avogadro’s number,  Kinetic theory postulates and specific heat capacities. Learning these topics is very important as numerous problems might appear in your exam based on this. You will get a strong base of fundamental concepts, which will also help them in your higher levels of education. NCERT Solutions for Class 11 Physics can be accessed using the links given below.

NCERT Solutions for Class 11 Physics Chapter Kinetic Theory will not only help you to form effective answers but also help you practice better. These solutions have been prepared strictly to the CBSE guidelines and come with suggested questions for your final and entrance exams. To avail these study materials offline, download NCERT Solutions for Class 11 Physics Chapter 12 PDF from Vedantu and enjoy uninterrupted learning.

Subtopics of Chapter 12 Kinetic Theory

  • Introduction

  • Molecular nature of matter

  • Behaviour of gases

  • Kinetic theory of an ideal gas

  • Law of equipartition of energy

  • Specific heat capacity

  • Mean free path

Kinetic Theory is the most scoring section in the CBSE Class 11 examination. The properties of gases are very easy to understand than those of solids and liquids. Everything is made of atoms – little particles that move around in perpetual motion, attracting each other when they are a little distance apart but repelling upon being squeezed into one another.Following are some key points of the kinetic theory of gases are given below.

  • Students should not have an exaggerated idea of the intermolecular distance in a gas. At ordinary pressures and temperatures are only 10 times or so the interatomic distance in solids and liquids. 

  • The pressure of any fluid is not only exerted on the wall. Pressure does exist everywhere in a fluid. Any layer of gas inside the volume of a container is in equilibrium position because the pressure is the same on both sides of the layer.

  • Air molecules in a room do not fall and settle on the ground (due to gravity) because of their high speeds and incessant collisions. In equilibrium position, there is a very slight increase in density at lower heights (like in the atmosphere).


The first part is all about a basic idea of the Kinetic Theory of gases and how it came into formulation, before jumping into the intricacies. You will learn about the structure and constituents of gas molecules, their properties as compared to liquids and solids, and their thermodynamic behaviour in this section. In NCERT Solutions Class 11 chp 12 Physics Kinetic Theory, questions related to terms like conduction, viscosity, diffusion and specific heat capacities have been explained with care and detailed form.

Molecular Nature of Matter

This section includes the details of the molecular behaviour of gas. This section talks about Atomic Theory and its laws. The importance of interatomic spaces, mean free path and dynamic equilibrium of gases has been discussed upon. Students will be required to understand Gay Lussac's Law and Avogadro’s Law and relation between them.

Behaviour of Gases

In this section, students are introduced to the title concept of Kinetic Theory of Gases and its postulates. This is a key section in NCERT Solutions for Class 11 Physics Chapter 12 and covers key terms and concepts like Boltzmann constant and Avogadro’s number, and their use in deriving relationships between temperature, pressure, and volume of gases. You will also be required to solve some numerical problems based on mole number and molar mass.

Kinetic Theory of an Ideal Gas

Further in this section divided into two subsections, where the already established concepts and relations are further discussed according to specific conditions.

Pressure of an Ideal Gas

With the constant velocities of gas particles, their momentum and eventually their pressure is deduced for calculation. A detailed explanation of Pascal’s Law is given in this section.

Kinetic Interpretation of Temperature

Incorporating the ideal gas equation with previous derivations, the relation between kinetic energy, pressure and temperature is derived with the aid of Boltzmann constant.

Chapter 12 Kinetic theory Physics Class 11 NCERT Solutions include examples and exercises relating to the above-mentioned concepts to reinforce the equations and derivations for efficient learning.

Law of Equipartition of Energy

This section spans over some of the important concepts of vibrational energy of molecules, rotational vibration, moment of inertia, and degrees of movement of gas particles are discussed before defining the Law of equipartition of energy.

Specific Heat Capacity

The Law of equipartition energy is used in the calculations of molar specific heat capacities of gases, solids and water at constant volume (cv) and constant pressure (cp) discussed in this section. Tips are also given on avoiding discrepancies in predicted and experimental values of specific heat capacity. Kinetic Theory of Gases Class 11 NCERT conveys the key of quantum physics and its application in solving numerical problems.

Mean Free Path

The last subtopic in Kinetic Theory of Gases Class 11 Physics defines the term mean free path and explains its course with the help of illustrative daily life examples. The formula to calculate it is also derived in relation to the size, density, and number of gas molecules in this section. You will find the perfectly explained guide to numerical based on the formula in Kinetic Theory of Gases Class 11 Physics NCERT Solutions that will help you improve on their problem-solving skills.

Benefits of NCERT Solutions for Class 11 Physics Chapter Kinetic Theory Of Gases

Class 11 physics chapter 12 NCERT solutions is a tool for simplified learning of ch 12.

  • The chapter of Kinetic Theory Class 11 NCERT covers some of the most important topics, each of which is discussed in the PDF in a very simple and easy manner.

  • Our NCERT Solutions for Class 11 Physics Chapter 12 are prepared by highly skilled expert physics teachers who are masters in the subject. Our expert team of professionals also comprises lecturers and PhD holders.

  • Good scores are important for each of us; we understand that. Thus, our Class 11 Physics Chapter 12 Kinetic Theory NCERT solutions streamline your efforts into scoring the highest possible marks.

  • The concepts of Physics cannot be brushed up. It must be clearly understood. We know your priority, that's  why we prepared these NCERT solutions.

  • A problem-solving approach with the help of NCERT physics Class 11 Chapter 12 solutions will solidify the foundation of your knowledge of the basics.

Frequently Asked Questions

Question 1. What is the Kinetic Theory of Gases?

Answer: Kinetic theory of gases is a theory revolving around the assumption of gas molecules as very tiny spherical particles or atoms, on the basis of which many fundamental gas properties are derived relating to their thermodynamic behaviour.

Question 2 : What are the subtopics of chapter 12 Kinetic Theory?

Answer: Following are the topics of chapter 12 KInetic Theory

  • Introduction

  • Molecular nature of matter

  • Behaviour of gases

  • Kinetic theory of an ideal gas

  • Law of equipartition of energy

  • Specific heat capacity

  • Mean free path