Electron gain enthalpy of fluorine is less than that of chlorine. Why?

Explanation

In F, the new electron to be added goes to 2p- subshell while in C1, it goes to 3p- subshell. Since 2p- subshell in much smaller that 3p- subshell therefore the added electron in F experiences much stronger repulsions from other electron in comparision to that in C1 in other words F does not accept the incoming electron a electron with that ease with which C1 accepts . consequently the electron gain enthalpy of F is less negative than that of C1