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 ground state is

Step-by-step solution

The energy of n th state in hydrogen like atom, E_ n =- 13.6 Z ² n² eV The energy of first excitation, aligned & E₂-E₁= -13.6 Z² (2)² + 13.6 Z² (1)² =40.8 (given) & Z²= 40.8 4 13.6 3 =4 aligned or Z=2 Energy needed to remove an electron from the ion in ground state, E=- (E₁ )=- [ -13.6 (2)² (1)² ]=54.4 eV