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

Options

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

Answer

C

Explanation

The addition of second electron in an atom or ion is always endothermic because of repulsion between two negative charges.