Kinetic Theory of Gases for JEE

• Pressure comes from molecular collisions with walls
• Average KE per molecule = (3/2)kT
• Each degree of freedom gets ½kT
• Monatomic f = 3, diatomic f = 5 (at room temperature)

• P = ⅓ρv_rms²
• v_rms = √(3RT/M), v_avg = √(8RT/πM), v_mp = √(2RT/M)
• Cᵥ = fR/2, γ = 1 + 2/f
• Mean free path λ = 1 / (√2 π d² n)

Printable Kinetic Theory of Gases formula sheet: formulas, key ideas and traps on one page. Save it as a PDF for offline revision.

• Using molar mass in g instead of kg in v_rms
• Taking f = 5 for monatomic gases
• Mixing up the order v_rms > v_avg > v_mp

Appears regularly; quick marks. Short, scoring chapter. One question is common.

Prerequisites: Thermodynamics.

Chapter names follow the current rationalised NCERT textbooks. Read these sections before solving PYQs.

Question. A vessel contains a mixture of helium (He, monatomic) and nitrogen (N₂, diatomic) at 300 K. The partial pressures are P_He = 2 atm and P_N₂ = 3 atm. (a) Find the ratio of rms speeds v_He : v_N₂. (b) Find the ratio of total internal energy U_He : U_N₂ in the vessel. (c) If the mean free path of N₂ is 2 × 10⁻⁷ m and its collision diameter is 3 × 10⁻¹⁰ m, calculate the number density of N₂ molecules. (M_He = 4 g/mol, M_N₂ = 28 g/mol)

This example was solved twice independently and both solutions agree.

Full-chapter free lectures picked from YouTube search results by views, from established JEE channels (mostly in Hinglish). Use the subtopic list to jump straight to the part you need (timestamps come from each video's own chapter list). Watch one, then solve PYQs the same day.

• KTG & THERMODYNAMICS in one Shot: All Concepts & PYQs Covered || JEE Main & Advanced — JEE Wallah, 8:34:44
  Jump to a subtopic (19)

  • 00:00 Introduction
  • 08:30 Assumptions
  • 18:30 Vrms terms
  • 26:06 Important results
  • 1:01:15 Graphs
  • 1:25:29 Thermodynamic process
  • 1:43:00 Work done by gas
  • 2:28:33 Degree of freedom
  • 2:40:01 Maxwell equipartition law
  • 3:14:07 1st law of thermodynamics
  • 3:34:21 Calculation of work done
  • 5:33:08 Molar specific heat
  • 6:00:02 Adabatic process
  • 6:38:22 Polytropic process
  • 7:18:03 Free Expansion
  • 7:28:48 2nd law of thermodynamics
  • 7:31:47 Carnot cycle and heat engine
  • 7:36:30 PYQs
  • 8:34:43 Thank You Bachhon!
• Kinetic Theory of Gases FULL CHAPTER | Class 11th Physics | Arjuna JEE — Arjuna JEE, 1:26:09
  Jump to a subtopic (12)

  • 00:00 Introduction
  • 04:03 Ideal Gas Assumptions
  • 11:51 Velocity Distribution
  • 21:20 Average RMS And Most Probable Speeds
  • 43:16 Pressure Exerted by Gas
  • 58:50 Kinetic Energy of Gas
  • 1:01:13 Gas Laws
  • 1:02:31 Boyle's Law
  • 1:04:22 Charle's Law
  • 1:06:54 Graham 's Law of Diffusion
  • 1:09:21 Mean Free Path , Collision Frequency , Average Relaxation Time
  • 1:25:13 Thank you, bacchon!

• 6 JEE Main 2026 PYQs on Kinetic Theory of Gases, with solutions.
• Read the chapter in NCERT textbooks (official, free), then solve its NCERT Exemplar (official, free) questions.
• Chapter-wise past questions: JEE Main and Advanced PYQs and question bank.
• Timed practice tests: NTA Abhyas practice tests (official, free) and our free mock tests.
• See it move: interactive simulation.