For the electron in the n = 4 orbit of a hydrogen atom, find these.

For a one-electron atom: $r_n = 52.9\ \text{pm} \times \dfrac{n^2}{Z}$, $E_n = -13.6\ \text{eV} \times \dfrac{Z^2}{n^2}$, $v_n = 2.19 \times 10^{6}\ \text{m s}^{-1} \times \dfrac{Z}{n}$. A jump gives a photon of energy $E_{\text{high}} - E_{\text{low}}$. $1\ \text{eV per atom} = 96.485\ \text{kJ mol}^{-1}$.