Which of the following is the energy required to take electron of ${\mathrm{He}}^{+}$ out of the force of nucleus if the energy of 1st shell of H atom is $-2.18\times {10}^{-18}\mathrm{J} {\mathrm{atom}}^{-1}$?

${\mathrm{E}}_{\mathrm{n}}=-2.18 \times {10}^{-18} \times \frac{{\mathrm{z}}^2}{{\mathrm{n}}^2}$

${\mathrm{E}}_2\left({\mathrm{He}}^{+}\right)=-2.18\times {10}^{-18} \times \frac{4}{4}=-2.18\times {10}^{-18}\mathrm{J}$

Energy required (+ve value) to take the electron away from the force of the nucleus will be $+2.18\times {10}^{-18}J.$