Two different gases 'A' and 'B' are filled in separate containers of equal capacity under the same condition of temperature and pressure. On increasing the pressure slightly the gas 'A' liquefies but gas B does not liquify even on applying high pressure until it is cooled. Explain this phenomenon.

Explanation

The temperature above which a gas cannot be liquefied howsoever high pressure may be applied on the gas is called critical temperature. Since, gas 'A' liquifies easily, this suggests gas 'A' is below its critical temperature.
On the other hand, gas 'B' does not liquefy easily even on applying high pressure. This suggests that gas 'B' is above its chitical temperature.