Successive ionization energy values increase Why ?

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 number of electrons .
(iii) Due to greater nuclear attraction second ionization energy is higher than first ionization energy.