Easy MCQ +4 / -1 PYQ · JEE Mains 2020

Match the ${{{C_P}} \over {{C_V}}}$ ratio for ideal gases with different type of molecules :

Molecule Type CP/CV
(A) Monatomic (I) 7/5
(B) Diatomic rigid molecules (II) 9/7
(C) Diatomic non-rigid molecules (III) 4/3
(D) Triatomic rigid molecules (IV) 5/3

  1. A (A)-(III), (B)-(IV), (C)-(II), (D)-(I)
  2. B (A)-(IV), (B)-(II), (C)-(I), (D)-(III)
  3. C (A)-(IV), (B)-(I), (C)-(II), (D)-(III) Correct answer
  4. D (A)-(II), (B)-(III), (C)-(I), (D)-(IV)

Solution

$\gamma = {C_p}/{C_v}$<br><br>${\gamma _A} = 1 + {2 \over 3} = 5/3$<br><br>${\gamma _B} = 1 + {2 \over 5} = 7/5$<br><br>${\gamma _C} = 1 + {2 \over 7} = 9/7$<br><br>${\gamma _D} = 1 + {2 \over 6} = 4/3$

About this question

Subject: Physics · Chapter: Thermodynamics · Topic: Zeroth and First Law

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