Q:- Write the trend of electron gain enthalpy in following?

F_(g),F^-_(g),Cl_(g),Cl^-_(g)

Electron gain enethalpy of Cl is highet here due to its small size and one electron short than noble gas configuration. The electron gain enthalpy of F is smaller than Cl despite of the fact that it is smaller than Cl. this iS because of it extremly small size due to which interelectronic repulsion takes place.
Followed by Cl- and F-
so the correct order would be
Cl > F> Cl- > F-