Gases possess characteristic critical temperature which depends upon the magnitude of intermolecular forces between the particles. Following are the critical temperatures of some gases.

Gases H2 He O2 N2
The critical temperature in Kelvin 33.2 5.3 154.3 126

From the above data, the order of liquefaction of the given gases is-
(write the order from the gas liquefying first)
1. H2, He, O2, N2
2. He, O2, H2, N2
3. N2, O2, He, H2
4. O2, N2, H2, He