RE-NEET 2026 Chemistry Trends in Properties MCQ Question

The correct trend in electron gain enthalpy is influenced by atomic size and effective nuclear charge. As you move from left to right across a period, electron gain enthalpy generally becomes more negative due to increased nuclear attraction. Chlorine (Cl) has a higher electron gain enthalpy than fluorine (F) because F's small size leads to greater electron-electron repulsion in its compact electron cloud. Thus, the trend is Cl > F > Br > I, as bromine (Br) and iodine (I) have larger atomic sizes and lower electron affinity.

The other options fail because they either misplace chlorine and fluorine or do not account for the increasing atomic size down the group.