The ionisation energy of an electron in the ground state of helium atom is 24.6V. The energy required to remove both the electron is :

Options

A. 51.8eV
B. 79eV
C. 38.2eV
D. 49.2eV

Answer

B

Explanation

Ionisation energy in ground state =24.6eV
Energy required to remove 2 electrons from `He^(2+)`
`=Z^(2) (13.6)eV =(2)^(2) (13.6) =54.4eV`
So, total energy required =24.6+54.4=79eV