Question

The energy required to remove the electron from a singly ionized Helium atom is $2.2$ times the energy required to remove an electron from Helium atom. The total energy required to ionize the Helium atom completely is:

• A. $20eV$
• B. $79eV$
• C. $109eV$
• D. $34eV$

Answer 1

Answer: (B)

$79eV$

Let $E_1$= energy required to remove $e^{-}$

from singly ionised Helium atom

=$\frac{+13.6z^2}{n^2}$

=$\frac{\left(13.6\right)(2{)}^2}{(1{)}^2}$

=$54.4eV$

$E_2$= energy required to remove an $e^{-}$ from He -atom

given $E_1=2.2E_2$

$\therefore E_2=\frac{E_1}{2.2}=\frac{54.4}{2.2}=24.7eV$

$\therefore$ Energy required to remove both $e^{-}$'s from He-atom

$=24.7+54.4$

$=79.1eV$