N₀/2atoms of X (g) r converted  into   X⁺ (g)   by energy E₁  N₀ /2  atoms  of  X(g) r converted into  X^--  by energy E₂ hence d ionization potential & EA of  X(g) r

Ionization potential is energy required to remove an electron FOR 1 MOLE..OR N_A ATOMS

Therefore,

N₀/2---->E₁ => N_A--->?  IE=2N_AE₁/ N₀..

Similarly FOR E=2N_AE₂/ N₀ .