The gas with the highest critical temperature is

The critical temperatures $(T_C)$ of some gases are given below:

Gases	$H_2, He, O_2$
$T_C \ (K)$	$33.2, 5.3, 154.3$

Based on the above data,what is the order of liquefaction of these gases? Start writing the order from the gas that liquefies first.

What is meant by the vapor of a substance like $CO_2$?

The critical temperature of $O_2$ is $154.3 \ K$ and the critical temperature of $N_2$ is $126.0 \ K$. Which gas will liquefy first during the liquefaction of air?

The liquified gas that is used in dry cleaning along with a suitable detergent is

Which set of conditions represents the easiest way to liquefy a gas?