a
Given number density of molecules of gas as a function of \(r\) is

\(n(r)=n_{0} e^{-a r^{4}}\)

Total number of molecule \(=\int_{0}^{\infty} n(r) \mathrm{d} V=\int_{0}^{\infty} n_{0} e^{-\alpha x^{4}} 4 \pi r^{2} d r\)

Number of molecules is proportional to \(\mathrm{n}_{0} \alpha^{-3 / 4}\)