The electron affinity of sulfur is........

The least stable ion 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:

The increasing order of electron affinity for $Cl, Br$ and $I$ is .....

Which of the following statements is correct?

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