Question

Let $\gamma_1$ be the ratio of molar specific heat at constant pressure and molar specific heat at constant volume of a monoatomic gas and $\gamma_2$ be the similar ratio of diatomic gas. Considering the diatomic gas molecule as a rigid rotator, the ratio, $\frac{\gamma_1}{\gamma_2}$ is :

• A. $\frac{21}{25}$
• B. $\frac{25}{21}$
• C. $\frac{35}{27}$
• D. $\frac{27}{35}$

Answer 1

Answer: (B)

For monoatomic gas $\gamma_1=\frac{5}{3}$
For diatomic gas at low temperatures
$\gamma_2=\frac{7}{5} $
$ \therefore \frac{\gamma_1}{\gamma_2}=\frac{\frac{5}{3}}{\frac{7}{5}}=\frac{25}{21}$