Diatomic molecules like hydrogen have energies due to both translational as well as rotational motion. From the equation in kinetic theory \(pV = \frac{2}{3}E\), E is
1
the total energy per unit volume.
2
only the translational part of energy because rotational energy is very small compared to the translational energy.
3
only the translational part of the energy because during collisions with the wall pressure relates to change in linear momentum.
4
the translational part of the energy because rotational energies of molecules can be of either sign and its average over all the molecules is zero.