Which is the correct order of second ionization potential of $$C, N, O$$  and $$F$$ in the following ?

Solution :
The second ionization potential means removal of electron from cation
$$\eqalign{ & {C^ + } = 1{s^2}2{s^2}2{p^1},{N^ + } = 1{s^2}2{s^2}2{p^2} \cr & {O^ + } = 1{s^2}2{s^2}2{p^3},{F^ + } = 1{s^2}2{s^2}2{p^4} \cr} $$
Therefore $$O > F > N > C$$