The correct order of the electron gain enthalpy of the given elements is

What is the correct order of electron affinity for the given groups?

The electron affinity of the following elements can be arranged as:

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

Which one of the elements has the maximum electron affinity?

Which of the following represents the correct order of electron affinity?