Question

For $n - l - 1 = 0,r_{mp} = \frac{n^{2}a_{0}}{z}$ and for all orbitals $r_{av} = \frac{n^{2}a_{0}}{z}\left\lbrack 1 + \frac{1}{2}\left( 1 - \frac{l(l + 1)}{n^{2}} \right) \right\rbrack$