Physics Circle home Student Login

Home›Chapters›Thermodynamics PYQs›Specific Heats of Gases - Cp, Cv, γ & Mayer's Relation›Question 11

JEE Main 2025 (22 Jan, Shift 2) · Specific Heats of Gases - Cp, Cv, γ & Mayer's Relation

Specific Heats of Gases - Cp, Cv, γ & Mayer's Relation question from JEE Main 2025 (22 Jan, Shift 2)

Q11JEE Main 2025 · 22 JAN · SHIFT 2Medium

Specific Heats of Gases - Cp, Cv, γ & Mayer's Relation

For a diatomic gas, if γ1=(CpCv)\gamma_1 = \left(\frac{C_p}{C_v}\right) for rigid molecules and γ2=(CpCv)\gamma_2 = \left(\frac{C_p}{C_v}\right) for another diatomic molecules, but also having vibrational modes. Then, which one of the following options is correct? (Cp and Cv are specific heats of the gas at constant pressure and volume)

Show answer and solution

Answer: (a)

  1. γ=1+RCV\gamma = 1 + \dfrac{R}{C_V}.
  2. Vibrational modes increase CVC_V, so γ\gamma decreases.
  3. Rigid: γ1=1.4\gamma_1 = 1.4; with vibration, e.g. γ2=97≈1.29\gamma_2 = \dfrac{9}{7} \approx 1.29.
  4. So the answer is (a) γ2<γ1\gamma_2 < \gamma_1.
Report a mistake

More questions on Specific Heats of Gases - Cp, Cv, γ & Mayer's Relation