Steps and reasons needed

1. A hermetically sealed box has a mixture of two gases in it, namely nitrogen gas and helium gas. The numbers of molecules of each gas is equal. The initial temperature is 300 K. The temperature of the box is reduced to 10 K. At this temperature He remains in the gaseous phase while nitrogen becomes solid, so that all nitrogen molecules stick to the walls permanently. Assume the volume of the box does not change. How does the pressure in the box change?

2. Radon is a radioactive gas with atomic weight 0.222 kg/mole. Assume that some amount of this gas is absorbed on a flat, perfectly polished surface. Thus the atoms can freely move on the surface forward and backward, or to the right and left. But the atoms stick to the surface so they cannot move up or down. (Such molecules are said to be effectively two dimensional.) Compute the average translational kinetic energy of a single radon molecule that is absorbed on the surface at room temperature (20° C)?