Question

For polyatomic molecules having 'f' vibrational modes, the ratio of two specific heats, $\frac{C_p}{C_v}$ is ............

• A. $\frac{1+f}{2+f}$
• B. $\frac{2+f}{3+f}$
• C. $\frac{4+f}{3+f}$
• D. $\frac{5+f}{4+f}$

Answer 1

Answer: (C)

$\frac{4+f}{3+f}$

By the law of equipartition of energy, for one mole of polyatomic gas
$C_p=(4+f)Rand{C}_v=(3+f)R$
$\therefore \frac{C_p}{C_v}=\frac{(4+f)R}{(3+f)R}=\frac{(4+f)}{(3+f)}$