Which intermolecular force is most responsible for allowing $Xe$ gas to liquefy?

Explain the liquefaction of real gases and permanent gases.

What happens when the temperature of $CO_2$ at its critical temperature of $30.98 \, ^\circ C$ is increased or decreased?

Critical temperature for carbon dioxide and methane are $31.1^{\circ} C$ and $-81.9^{\circ} C$ respectively. Which of these has stronger intermolecular forces and why?

At what point does surface tension vanish?

Critical temperatures for $A$,$B$,$C$ and $D$ gases are $25\,^{\circ}C$,$10\,^{\circ}C$,$-80\,^{\circ}C$ and $15\,^{\circ}C$ respectively. Which gas will be liquefied more easily?