Question

explain the electron gain enthalpy?

Answer 1

Electron Gain Enthalpy is the energy released when one mole of electron are added to gaseous atoms of an element. Electron Affinity is the same as Electron Gain Enthalpy but viewed as the energy supplied to the surroundings rather than that released by the atoms. Hence its sign is opposite from the latter.

Answer 2

the enthalpy change that occurs when we add an electron to an outermost shell of an atom is called  electron gain enthalpy