The first electron gain enthalpy of oxygen is $-141 \mathrm{~kJ} \mathrm{~mol}^{-1}$, its second electron gain enthalpy is :

The first ionisation enthalpy of Al in $\mathrm{kJ} \mathrm{mol}^{-1}$ is: [Given the first ionisation enthalpy of $\mathrm{Na}, \mathrm{Mg}$ and Si in $\mathrm{kJ} \mathrm{mol}^{-1}$ are 497,738 and 787 respectively]