Question

Which of the following will have the most negative electron gain enthalpy and which the least negative?

P, S, Cl, F

Answer 1

Halogens have the highest negative value of electron gain enthalpy. Here Cl and F both are halogens but electron gain enthalpy of Cl is more negative than F because of the very small size of F which causes interelectronic repulsion among its electrons.

Cl has the most negative one. P has the least negative one due to the larger size.