The energy of second orbit of hydrogen is equal to the energy of

$\begin{array}{l}\mathrm{E}=-\frac{{\mathrm{Z}}^2}{{\mathrm{n}}^2}\times 13.6\mathrm{eV}\\ {\mathrm{E}}_2=-\frac{13.6}{4}\mathrm{for}\text{'}\mathrm{H}\text{'}\\ \mathrm{E}=-\frac{{\mathrm{Z}}^2}{{\mathrm{n}}^2}\times 13.6\mathrm{eV}\\ -\frac{13.6}{4}=-\frac{{\mathrm{Z}}^2}{{\mathrm{n}}^2}\times 13.6\\ \frac{{\mathrm{Z}}^2}{{\mathrm{n}}^2}=\frac{1}{4}\left(\mathrm{Z}=2,\mathrm{n}=4\right)\end{array}$