Correct Option (d) I, III, II, IV
Explanation:
The given electronic configuration of elements corresponds to
Electron affinity genergally increases from left to right on moving along a period which it decreases down the group.
But electron affinities of groups 18 and 15 elements are more positive [less electronegative] than 16 group elements due to stable electronic configuration. While group 17 elements have highest value of electron affinity [more negative].
Though F and Cl belongs to group 17 elements but Cl possesses larger electron affinity than F although F is more electronegative than Cl because F has very small size due to which the additional electron repels 2p electrons.
This results in less evolution of energy in the formation of F- ion. Hence, the decreasing order of affinity for the given electronic configuration is
i > iii > ii > iv
(Cl) (F) (N) (Ar)