Question:
Within each pair of elements $\mathrm{F} \& \mathrm{Cl}, \mathrm{S} \& \mathrm{Se}$, and $\mathrm{Li} \& \mathrm{Na}$, respectively, the elements that release more energy upon an electron gain are:
Correct Option: , 2
Solution:
Generally, electron affinity decreases on moving down a group. Chlorine has more electron affinity than F because of very small size of fluorine. Therefore chlorine, sulphur and Li has higher electron affinity among given groups.