ionized helium atom \({ = \frac{{(13.6){Z^2}}}{{{1^2}}} = 54.4\,{\text{eV}}}\)
\((\because Z=2)\)
Energy required to remove \(e^-\) from helium atom \(=x\,eV\)
According to question, \(54.4 \mathrm{eV}=2.2 \mathrm{x} \Rightarrow \mathrm{x}\)
\(=24.73 \mathrm{eV}\)
Therefore, energy required to ionize helium atom \(=(54.4+24.73)eV\) \(=79.12 \mathrm{eV}\)