When the first electron gain enthalpy
Question:

When the first electron gain enthalpy $\left(\Delta_{\text {eg }} \mathrm{H}\right)$ of oxygen is $-141 \mathrm{~kJ} / \mathrm{mol}$, its second electron gain enthalpy is :

1. almost the same as that of the first

2. negative, but less negative than the first

3. a positive value

4. a more negative value than the first

Correct Option: , 3

Solution:

Second electron gain enthalpy is always positive for every element.

$\mathrm{O}_{(\mathrm{g})}^{-}+\mathrm{e}^{-} \rightarrow \mathrm{O}_{(\mathrm{g})}^{-2} \quad ; \Delta \mathrm{H}=$ positive