$1$B$.9$ The spread of pollutants through the atmosphere is governed partly by the effects of winds but also by the natural tendency of molecules to diffuse. The latter depends on how far a molecule can travel before colliding with another molecule. Calculate the mean free path of diatomic molecules in air using $=0\mathrm{.}43n{m}^2$ at $25C$ and $($a$)\frac{10}{b}ar,($b$)103$kPa, $($c$)1\mathrm{.}0Pa.$