Question

Suppose the distance between the atoms of a diatomic gas remains constant. Its specific heat at constant volume per mole is

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

Answer 1

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

Since, the distance between atoms of the given diatomic gas remains constant, hence the molecule is not vibrating. This means gas is at room temperature.
Therefore, total degrees of freedom of an atom of a diatomic gas is 5 which are 3 translational and 2 rotational.
Thus specific heat at constant volume per mole,
$\Rightarrow C_v=\frac{fR}{2}$
$\Rightarrow C_v=\frac{5R}{2}$