Question

The average rotational kinetic energy for the diatomic gas molecules is $(k_B$ is Boltzmann constant and $T$ is absolute temperature)

• A. $\frac{3}{2}{k}_{B}T$
• B. $\frac{7}{2}{k}_{B}T$
• C. $k_{B}T$
• D. $\frac{5}{2}{k}_{B}T$

Answer 1

The correct option is C $k_{B}T$

The average thermal energy for gas molecules per degree of freedom $=\frac{1}{2}{k}_{B}T$
For diatomic gas, rotational degree of freedom is $2$.

So, average rotational kinetic energy for diatomic gas molecules
$=k_{B}T$