Which of the following represents correct order of electron affinity? — Periodic Table and Periodicity Chemistry Question

💡 Solution & Explanation

Step 1: Halogens (Cl, F) have significantly higher electron affinities than chalcogens (S, O) because they are only one electron away from a stable octet. Step 2: Within a group, 3rd-period elements (Cl, S) have higher electron affinities than their corresponding 2nd-period elements (F, O) because the smaller size of 2nd-period atoms causes severe interelectronic repulsion in their compact 2p orbitals. Step 3: This gives the orders Cl > F and S > O. Putting it all together, the correct order is Cl > F > S > O, which is option (a).