CBSE 11 Physics · U9
Behaviour of Perfect Gases and Kinetic Theory of Gases
CBSE Class 11 Physics Unit IX: equation of state of a perfect gas, work done in compressing a gas, kinetic theory assumptions, pressure, kinetic interpretation of temperature, rms speed, degrees of freedom, equipartition, specific heat capacities, mean free path, and Avogadro's number.
Test yourself
A focused, distraction-free run through 25 multiple-choice questions. Hints if you need them; your score at the end.
Difficulty guide
The label describes the problem, not your ability.
1/5 - Foundational
Warm-up setup; checks one basic idea.
2/5 - Routine exam skill
Normal syllabus skill; usually one main rule or interpretation.
3/5 - Standard multi-step
Exam-style problem with multiple steps or a common trap.
4/5 - Hard exam skill
High-end exam problem; combines methods carefully.
5/5 - Challenge
Stretch problem beyond normal exam pressure.
Topic 9.1
Perfect Gas Equation and Compression Work
Equation of state of a perfect gas, gas-law proportional reasoning, P-V graphs, and work done in compression or expansion.
Topic 9.2
Kinetic Theory Assumptions and Pressure
Ideal-gas assumptions, molecular collisions with container walls, pressure from momentum transfer, and the relation between pressure, density, and rms speed.
Topic 9.3
Temperature and RMS Speed
Kinetic interpretation of absolute temperature, average translational kinetic energy, rms speed, and molecular-mass dependence.
Topic 9.4
Degrees of Freedom, Equipartition and Specific Heats
Degrees of freedom, statement of equipartition of energy, and applications to molar heat capacities of ideal gases.
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Topic 9.5
Mean Free Path and Avogadro Number
Mean free path, number density, pressure-temperature dependence of collision spacing, and Avogadro's number as particles per mole.