Question

An energy of $24.6\text{eV}$ is required to remove one of the electrons from a neutral helium atom. The energy $\left(\text{in}\text{eV}\right)$ required to remove both the electrons from a neutral helium atom is

• A. $38.2$
• B. $49.2$
• C. $51.8$
• D. $79.0$

Answer 1

The correct option is D $79.0$

After remaining one electron from Helium atom is will become Hydrogen like atom.
Energy required to remove remaining one electron is
$E=\left(13.6\right)\frac{Z^2}{n^2}=\left(13.6\right)\frac{2^2}{1^2}=56.4\text{eV}$
Energy required to remove both electrons is $24.6\text{eV}+54.4\text{eV}=79\text{eV}$