A mixture of ideal gas is cooled upto liquid helium temperature (4.22K) to form an ideal solution

In the van der Waal's equation (P + $${{{n^2}a} \over {{V^2}}}$$)(V - nb) = nRT the constant 'a' reflects the actual volume of the gas molecules.

Kinetic Energy of a Molecule is zero at 0^oC.

A gas in a closed container will exert much higher pressure due to gravity at the bottom than at the top.