The excititation energy of a hydrogen -like ion in its first excitedstate is `40.8 eV` Find the energy needed to remain the electron from the ion

Explanation

The excitation energy in the first excited state is
`E = RhcZ^(2)((1)/(1^(2)) - (1)/(2^(2)))`
`= (13.6 eV) xx Z^(2) xx(3)/(4)`
Equation this to `40.8eV` we get `Z= 2` So, that in question is `He^(+)` The energy of the ion in the ground state is
`E = (RhcZ6(2))/(1^(2)) = -4 xx (13.6 eV)`
`= - 54.4 eV`
Thus `54.4eV` is required to remain the electron from the ion