Question

The formation of the oxide ion $O^{2-}\left(g\right)$ requires first an exothermic and then an endothermic step as shown below.
$O+e^{-}\to O_{\left(g\right)}^{-}+142KJmol{e}^{-1};O^{-}+e^{-}\to O_{\left(g\right)}^{-2}-844KJmol{e}^{-1}$
This is because :

• A. Oxygen is more electronegative
• B. Oxygen has high electron affinity
• C. $O^{-}$ ion lends to resist the addition of another electron
• D. $O^{-}$ ion has comparatively larger size than oxygen atom.

Answer 1

Answer: (B), (C)

The correct options are
B Oxygen has high electron affinity
C $O^{-}$ ion lends to resist the addition of another electron

The formation of the oxide ion $O^{-2}\left(g\right)$ required first an exothermic and then an exothermic step as shown below.
$O+e^{-}\to O_{\left(g\right)}^{-}+142KJmol{e}^{-1}$; This is because oxygen has high electron affinity.
$O^{-}+e^{-}\to O_{\left(g\right)}^{-2}-844KJmol{e}^{-1}$; This is because anion formed resists addition of another electron.