Among ${\mathrm{O}}^{\mathrm{x}}, {\mathrm{O}}^{\mathrm{y}}$ and ${\mathrm{O}}^{\mathrm{z}}$, which will have the maximum value of electron affinity?

$\mathrm{x}$, $\mathrm{y}$ and $\mathrm{z}$ are $0$, $-1$ and $-2$, respectively.

The amount of energy released when ${10}^{12}$ atoms of $\mathrm{Cl}$ vapours are converted into ${\mathrm{Cl}}^{-}$ ions according to the equation $\mathrm{Cl} \left(\mathrm{g}\right)+{\mathrm{e}}^{-}⟶{\mathrm{Cl}}_{}^{-} \left(\mathrm{g}\right)$ is $58\times {10}^{-10} \mathrm{J}$. Calculate ${\mathrm{\Delta }}_{\mathrm{eg}}\mathrm{H}$ of $\mathrm{Cl}$ atom in $\mathrm{kJ} {\mathrm{mol}}^{-1}$ or $\mathrm{eV} {\mathrm{atom}}^{-1}$.

Arrange the elements with the following electronic configuration of valence electron in the decreasing order of ${\mathrm{\Delta }}_{\mathrm{eg}}{\mathrm{H}}^{\mathrm{\Theta }}$.

(A) $3{\mathrm{s}}^{2}3{\mathrm{p}}^4$ (B) $2{\mathrm{s}}^{2}2{\mathrm{p}}^4$ (C) $2{\mathrm{s}}^{2}2{\mathrm{p}}^3$ (D) $2{\mathrm{s}}^{2}2{\mathrm{p}}^5$

Select the equations having endothermic step: