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Chemistry Question on Classification of elements & periodicity in properties

The formation of the oxide ion O2−(g)O^{2-}(g) requires first an exothermic and then an endothermic step as shown below O(g)+e−O−(g)?H∘=−142kJmol−1O\left(g\right) + e^{-}O^{-} \left(g\right)?H^{\circ} = -142kJmol^{-1} O−(g)+e−O2−(g)?H∘=844kJmol−1O^{-} \left(g\right) + e^{-}O^{2-} \left(g\right)?H^{\circ} = 844kJmol^{-1}

A

Oxygen is more electronegative

B

O−O^- ion has comparatively larger size than oxygen atom

C

O−O^- ion will tend to resist the addition of another electron

D

Oxygen has high electron affinity

Answer

O−O^- ion will tend to resist the addition of another electron

Explanation

Solution

O−1(g)+e⟶O−2(g)O^{-1}\left(g\right) + e \longrightarrow O^{-2}\left(g\right) Due to the electronic repulsion, amount of the energy is needed to add electron