ChemistryMedium127×since 2002Q1586The formation of the oxide ion O²⁻(g) requires first an exothermic and then an endothermic step as shown below O_(g) + e⁻ = O(g)−O_{(g)}^{-}O(g)− Δ\DeltaΔH^o = -142 kJmol⁻¹ O(g)−O_{(g)}^{-}O(g)− + e⁻ = O(g)2−O_{(g)}^{2-}O(g)2− Δ\DeltaΔH^o = 844 kJmol⁻¹ This becauseAO⁻ ion will tend to resist the addition of another electronBOxygen has high electron affinityCOxygen is more electronegativeDO⁻ ion has comparatively larger size than oxygen atomCheck answerSkip