All gases except __________ shows a cooling effect during throttling process at atmospheric temperature and pressure.

Solution(By Examveda Team)

Since all the gases except $${H_2}$$ $$He$$ etc, have maximum inversion point greater than atmospheric (room) temperature cooling can take place by throttling if the initial conditions lie in a region where joule thomson coefficient is positive. But for $${H_2}$$ the maximum inversion point is very low so usually heating takes place by throttling. But if we do the decrease the temperature of $${H_2}$$ from room temperature to below the maximum inversion point temperature by some primary cooling techniques than there are chances where cooling of $${H_{2\,gas}}$$ can be done by throttling.