Excitation energy of a hydrogen like ion in its first excitation state is 40.8 eV. Energy needed to remove the electron from the ion in gruond state is

Options

A. 54.4 eV
B. 13.6 eV
C. 40.8 eV
D. 27.2 eV

Answer

A

Explanation

excitation energy ` Delta E = E_2 -E_1 = 13.6 Z^2 [(1)/(I^2) - (1)/(2^2)]`
`implies 40.8 = 13.6 xx (3)/(4) xx Z^2 implies Z=2`
Now required energy to remove the electron from ground state `= ( + 13.6 Z^2 ) /((1)^2) = 13.6 (Z )^2 = 54.4 eV `