Which sequence correctly represents the increasing order of electron gain enthalpy (with negative si — Periodic Table and Periodicity Chemistry Question

💡 Solution & Explanation

In general, halogens > chalcogens. Within the groups, the 3rd period has a higher magnitude than the 2nd period due to less inter-electronic repulsion. Therefore, $O < S$ and $F < Cl$. Combined order: $O < S < F < Cl$.