Statement (A) : The magnitude of E.A. depends on atomic size and electronic configuration

Statement (B) : The energy released when an electron is added to a valence shell of an neutral gaseous atom is called E.A.

Statement (C) : Electron gain enthalpy decreases with increase in the atomic number across a period.

Statement -A: The smaller is the size of the atom the stronger is the attraction for the added electron towards the nucleus , the element with stable configuration has very little or no tendency to accept additional electron.

Statement-B: is correct because its perfect definition of electron affinity.

Statement-C: is incorrect, the correct statement is electron gain enthalpy increases with increase in the atomic number across a period.