The formation of the oxide ion `O_(g)^(2-)` requires first an exothermic and then an endothermic step as shown below:
`O_(g)+e^(-) rarr O_(g)^(-)`, `DeltaH=-142 kJ mol^(-1)`
`O(g)+e rarr O_(g)^(2-)`, `DeltaH=844kJ mol^(-1)`
This is because:

Options

A. `O^(-)` ions has comparatively larger size than oxygen atom
B. Oxygen has high electrons affinity
C. `O^(-)` ion will tend to resist the addition of another electron
D. Oxygen is more electronegative

Answer

C