Write the degrees of freedom for:
$(i)$ Monoatomic gas
$(ii)$ Diatomic gas

(N/A) The degree of freedom $(f)$ is defined as the number of independent ways in which a molecule can possess energy.
$(i)$ For a monoatomic gas (e.g.,$He, Ne, Ar$),the molecule can only have translational motion along the $x, y,$ and $z$ axes. Thus,it has $3$ translational degrees of freedom and $0$ rotational degrees of freedom. Total degrees of freedom $f = 3$.
$(ii)$ For a diatomic gas (e.g.,$H_2, O_2, N_2$) at room temperature,the molecule has $3$ translational degrees of freedom and $2$ rotational degrees of freedom (about the axes perpendicular to the bond axis). Total degrees of freedom $f = 3 + 2 = 5$.