Among halogens, the correct order of amount of energy released in electron gain (electron gain enthalpy) is-

1. F > Cl > Br > I 2. F < Cl < Br < I
3. F < Cl > Br > I 4. F < Cl < Br < I

HINT: Generally down the group electron gain enthalpy decreases.

Explanation:
As we move from Cl to I, the electron gain enthalpy (i.e., energy released in electron gain) become less and less negative due to a corresponding increase in the atomic size.
However, the electron gain enthalpy of F is less negative than that of Cl due to its small size.
Thus, the negative electron gain enthalpy follows the order : F<Cl>Br>I