Question

Arrange $S,O$ and $Se$ in ascending order of their electron affinity.

• A. $Se<S<O$
• B. $O<Se<S$
• C. $S<O<Se$
• D. $S<Se<O$

Answer 1

The correct option is B $O<Se<S$

$Se,S$ and $O$ are members of group $16$. Now in a group electron affinity decreases down a group. therefore, the electron affinity of S is more than oxygen due to small size of oxygen.

Addition of extra electron to the oxygen causes more inter-electronic repulsion and electron affinity decreases.

Therefore correct order of EA is $S>Se>O$.