An energy of 25.6eV. Is required to remove one of the electrons froma a neutral helium atom. What is the energy (in eV) required to remove both the electrons from a neutral helium atom ?

Options

A. a) 50 eV
B. b) 60 eV
C. c) 70 eV
D. d) 80 eV

Answer

D

Explanation

To remove one electron from the helium atom, having two electron energy required = 25.6 eV.
But after removing the first electron, the remaining atom becomes a hydrogen like atom. Hence to remove the second electron from the ground state of helium atom energy required
= Ionisation energy `=+(13.6Z^2)/(1) = (13.6xx4)/(1)`
=54.4 eV
`therefore` Total energy required = 25.6 + 54.4 = 80 eV