# Within each pair of elements

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:

1. $\mathrm{Cl}, \mathrm{Se}$ and $\mathrm{Na}$

2. $\mathrm{Cl}, \mathrm{S}$ and $\mathrm{Li}$

3. $\mathrm{F}, \mathrm{S}$ and $\mathrm{Li}$

4. $\mathrm{F}$, Se and $\mathrm{Na}$

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.