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If one mole of the polyatomic gas is having two vibrational modes and β is the ratio of molar specific heats for polyatomic gas [β = Cp/Cv], then the value of β is:
- 1.02
- 1.2
- 1.25
- 1.35
Correct answer: 1.2
Solution
Degrees of freedom f = 3 (trans) + 3 (rot) + 2x2 (two vibrational modes) = 10. So Cv = (f/2)R = 5R, Cp = 6R, and beta = Cp/Cv = 6/5 = 1.2.
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