Which are the most favorable conditions for the liquefaction of a gas?

At what point does surface tension vanish?

Under what conditions will an ideal gas,which follows the kinetic gas equation,undergo liquefaction?

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

$Gases$	$H_2$	$He$	$O_2$	$N_2$
$Critical \ temperature \ (K)$	$33.2$	$5.3$	$154.3$	$126$

From the above data,what would be the decreasing order of liquefaction of these gases?

According to Andrews isothermals,at what temperature does carbon dioxide gas start to condense at $73 \ atm$ (in $^{\circ} C$)?

$A$ gas can be liquefied at temperature $T$ and pressure $p$ provided: