Which will have the maximum value of electron affinity among $O^x, O^y$ and $O^z$ ($x, y$ and $z$ are $0, -1$ and $-2$ respectively)?

Increasing order of electron affinity is :-

What will be the value of $\Delta H$ for the following process?
$X_{(g)} + e^- \to X^-_{(g)}$

$A = 1s^2\, 2s^2\, 2p^4$,$B = 1s^2\, 2s^2\, 2p^5$,$C = 1s^2\, 2s^2\, 2p^6$. $A, B$ and $C$ are atoms/anions of the same element. Which one is correct? (One of $A/B/C$ is a neutral atom)

Choose the correct order of $\Delta H_{eg}$ ?
$(\Delta H_{eg} = \text{electron gain enthalpy})$

The equation used to represent the electron gain enthalpy is