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Physics · Kinetic Theory of Gases

JEE Main 2026 — 4 April, Evening Shift — Question 8

Assertion A: If the average kinetic energy of H2\mathrm{H}_2 and O2\mathrm{O}_2 molecules, kept in two different sized containers are same, then their temperatures will be same.

Reason R: The r.m.s. speed of H2\mathrm{H}_2 and O2\mathrm{O}_2 molecules are same at same temperature.

  1. Option A:

    Both A and R are true and R is the correct explanation of A

  2. Option B:

    Both A and R are true but R is NOT the correct explanation of A

  3. Option C:

    A is true but R is false

    Correct
  4. Option D:

    A is false but R is true

Answer: C

Step-by-step solution

Average kinetic energy per molecule = f2kT\frac{f}{2}kT, same KE implies same temperature (A true). But rms speed vrms=3RT/Mv_{rms} = \sqrt{3RT/M} depends on molar mass, so at same temperature rms speeds are different (R false).

Answer key and solution verified before publishing.

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Exam
JEE Main 2026
Paper
4 April, Evening Shift
Subject
Physics
Chapter
Kinetic Theory of Gases
Topic
Pressure of Gas and Different speeds of Gas Molecules
Assertion A: If the average kinetic energy of H 2 and O 2 molecules… | JEE Main 2026 PYQ with Solution · DhiX AI