Problem 2.227

Oxygen is enclosed at the temperature \(0^{\circ} \mathrm{C}\) in a vessel with the characteristic dimension \(l=10 \mathrm{~mm}\) (this is the linear dimension determining the character of a physical process in question). Find: (a) the gas pressure below which the mean free path of the molecules \(\lambda>l\) (b) the corresponding molecular concentration and the mean distance between the molecules.