Question

According to law of equipartition of energy the molar specific heat of a diatomic gas at constant volume where the molecule has one additional vibrational mode is:-

• A. $\frac{3}{2} R$
• B. $\frac{7}{2} R$
• C. $\frac{9}{2} R$
• D. $\frac{5}{2} R$

Answer 1

Answer: (B)

$\frac{7}{2} R$

Answer 2

The correct answer is (B) : $\frac{7}{2} R$
Diatomic gas molecules have three translational degree of freedom, two rotational degree of freedom & it is given that it has one vibrational mode so there are two additional degree of freedom corresponding to one vibrational mode, so total degree of freedom =7
Cv?=2fR?=27R?