Among the options, the element with the highest electron gain enthalpy is

The formation of the oxide ion $O^{2-}_{(g)}$ requires first an exothermic and then an endothermic step as shown below:
$O_{(g)} + e^{-} \to O^{-}_{(g)}; \Delta H = -142 \, kJ \, mol^{-1}$
$O^{-}_{(g)} + e^{-} \to O^{2-}_{(g)}; \Delta H = 844 \, kJ \, mol^{-1}$
This is because:

Evaluate the following statements regarding electron affinity $(EA)$:
$A$. Carbon is greater than fluorine
$B$. Sulphur is lesser than fluorine
$C$. Iodine is higher than bromine
$D$. Chlorine is greater than sulphur
Select the correct sequence of truth values ($T$ for true,$F$ for false):

What is the correct order of electron affinity for $B, C, N$,and $O$?

The correct order of electron gain enthalpy of $N$,$O$,$Cl$,$Al$ is

The formation of the oxide ion $O_{(g)}^{2-}$ requires first an exothermic and then an endothermic step as shown below. This is because
$O_{(g)} + e^{-} \rightarrow O_{(g)}^{-}; \Delta H^{o} = -142 \ kJ \ mol^{-1}$
$O_{(g)}^{-} + e^{-} \rightarrow O_{(g)}^{2-}; \Delta H^{o} = 844 \ kJ \ mol^{-1}$