$Reason :$ When a gas is heated at constant volume some extra heat is needed compared to that at constant pressure for doing work in expansion.
(Molecular weight of oxygen is $32 \,g / mol$ $\left. R =8.3 \,J K ^{-1} mol ^{-1}\right)$
Statement $I :$ In a diatomic molecule, the rotational energy at a given temperature obeys Maxwell's distribution.
Statement $II :$ In a diatomic molecule, the rotational energy at a given temperature equals the translational kinetic energy for each molecule.
In the light of the above statements, choose the correct answer from the options given below: