Chapter Exam

Chapter 9: Kinetic Theory of Gases — Online MCQ Test

Q: According to the kinetic theory of gases, gas molecules are assumed to be in continuous ______.

Answer: B. random motion — The kinetic theory states that gas molecules move continuously and randomly in all directions. This random motion is responsible for gas pressure and other macroscopic properties.

Q: Which of the following is NOT one of the postulates of the kinetic theory of gases?

Answer: D. Gas molecules move only along fixed paths — Gas molecules do not move along fixed paths; they move randomly and continuously. The other statements are standard assumptions of kinetic theory.

Q: For a fixed number of gas molecules at constant temperature, if the volume is reduced, the mean free path generally:

Answer: B. decreases — Reducing volume increases molecular number density, so collisions occur more frequently. Hence the mean free path decreases.

PHYSICS · CLASS 11th · Tamil Nadu State Board

Practice Chapter 9: Kinetic Theory of Gases with a free chapter-wise online MCQ test for Tamil Nadu State Board CLASS 11th PHYSICS. This chapter covers: This chapter details molecular nature of matter kinetic theory postulates pressure expression and temperature equivalence. Students study degree of freedom law of equipartition of.... AI-generated questions from basic to board-exam level, with instant results and explanations.

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Chapter 9: Kinetic Theory of Gases — Important Questions & Answers (FAQ)

Frequently asked questions from Tamil Nadu State Board CLASS 11th PHYSICS — Chapter 9: Kinetic Theory of Gases, with answers and explanations. These are sample questions; the exam has its own separate question set.

According to the kinetic theory of gases, gas molecules are assumed to be in continuous ______.

A. rest
B. random motion ✓
C. circular motion only
D. oscillatory motion only

Answer: B. random motion
The kinetic theory states that gas molecules move continuously and randomly in all directions. This random motion is responsible for gas pressure and other macroscopic properties.

The pressure exerted by a gas in a container is due to:

A. attraction between molecules
B. weight of the molecules only
C. collisions of molecules with the container walls ✓
D. increase in the size of molecules

Answer: C. collisions of molecules with the container walls
Gas pressure arises because molecules collide with the walls of the container and transfer momentum. The repeated collisions produce a force per unit area.

Which of the following is NOT one of the postulates of the kinetic theory of gases?

A. Gas molecules are in constant random motion
B. Molecules obey Newton's laws of motion
C. Intermolecular force is negligible except during collision
D. Gas molecules move only along fixed paths ✓

Answer: D. Gas molecules move only along fixed paths
Gas molecules do not move along fixed paths; they move randomly and continuously. The other statements are standard assumptions of kinetic theory.

For a fixed number of gas molecules at constant temperature, if the volume is reduced, the mean free path generally:

A. increases
B. decreases ✓
C. remains the same
D. becomes zero

Answer: B. decreases
Reducing volume increases molecular number density, so collisions occur more frequently. Hence the mean free path decreases.

Which statement is correct regarding the root mean square speed of gas molecules?

A. It decreases with increase in temperature
B. It is proportional to the square root of absolute temperature ✓
C. It is independent of molecular mass
D. It is equal to the arithmetic mean speed for all gases

Answer: B. It is proportional to the square root of absolute temperature
The rms speed is given by c_rms = √(3kT/m), so it varies as the square root of absolute temperature. It also depends inversely on the square root of molecular mass.

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