\(\&\) total energy \(=2.6+0=2.6\, {eV}\)
Finally in first excited state of \({H}\) atom total energy \(=-3.4 \,{eV}\)
Loss in total energy \(=2.6-(-3.4)\)
\(\quad\quad\quad\quad\quad\quad\quad\quad=6\,eV\)
It is emitted as photon
\(\lambda=\frac{1240}{6}=206\, {nm}\)
\({f}=\frac{3 \times 10^{8}}{206 \times 10^{-9}}=1.45 \times 10^{15} \,{Hz}\)
\(=1.45 \times 10^{9}\, {Hz}\)