Question

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

• A. $2$
• B. $49.2$
• C. $51.8$
• D. $79.0$

Answer 1

Answer: (D)

$79.0$

Energy to remove one electron is, $E_1=24.6$ $eV$

The energy required to remove the second electron is

$E_2=Z^{2}Rhc(\frac{1}{1^2}-\frac{1}{{\infty }^2})=2^2\times 13.6$ $eV=54.4$ $eV$

Therefore total energy required $E=E_1+E_2=24.6+54.4=79.0$ $eV$