Question

If the distance between the atoms of a diatomic gas remains constant. Its specific heat capacity at constant volume per gram-mole is

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

Answer 1

The correct option is A $\frac{5}{2}R$

As distance between the atoms of a diatomic gas remains constant, vibrational degree of freedom will not be counted.
$\therefore$ It possesses only translational and rotational degree of freedom.
$\Rightarrow f=3\left(\text{translational}\right)+2\left(\text{rotational}\right)=5$
Since, specific heat at constant volume per gram-mole is molar specific heat at constant volume.
$\Rightarrow C_V=\left(\frac{f}{2}\right)R$
$\therefore C_V=\frac{5}{2}R$