One of the lines in the emission spectrum of Li^ 2+ has the same...

For $2^{\text{nd line\text{ of }\text{ Balmer }\text{ series }\text{ in }\text{ hydrogen } }}$ spectrum $\frac{1}{\lambda}=\mathrm{R}(1)$\left(\frac{1}{2^{2}}-\frac{1}{4^{2}}\right)=\frac{3}{16} \mathrm{R} \text{ For } \mathrm{Li}^{2+}\left[\frac{1}{\lambda}=\mathrm{R} \times9\left(\frac{1}{\mathrm{x}^{2}}-\frac{1}{12^{2}}\right)=\frac{3 \mathrm{R}}{16}\right]$which is satisfied by$n=12 \rightarrow n=6