How would you explain the fact that the second ionisation potential is always higher than first ionisation potential ?

Explanation

(i) Second ionization potential is always higher than first ionization potential.
(ii) Removal of one electron from the valence orbit of a neutral gaseous atom is easy so first ionization energy is less. But from a unipositive ion, removal of one more electron becomes difficult due to the more forces of attraction between the excess of protons and less numberof electrons.
(iii) Due to greater nuclear attraction, second ionization energy is higher than first ionization energy