d
\(\frac{1}{\lambda } = \bar \nu = R{Z^2}\left( {\frac{1}{{n_1^2}} - \frac{1}{{n_2^2}}} \right)\)

\(\Rightarrow\) \(\bar \nu \propto {Z^2}\)

\(\Rightarrow\) \(\frac{{{{\bar \nu }_2}}}{{{{\bar \nu }_1}}} = {\left( {\frac{{{Z_2}}}{{{Z_1}}}} \right)^2} = {\left( {\frac{Z}{1}} \right)^2} = 4\)

\(\Rightarrow\) \({\bar \nu _2} = \bar \nu \times 4 = 81588\,c{m^{ - 1}}\).