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The formation of the oxide ion O^2-( g) requires first an exothermic and then an endothermic step as shown below O( g)+ e^- O^-( g) Δ H°=-142…

JEE Main 2004 — Chemistry Physical Chemistry

2004mcqmedium

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

Official previous-year question

Held on 30 Apr 2004 · Verified 6 Jul 2026.

Options

  1. A

    Oxygen is more electronegative

  2. B

    O−\mathrm{O}^{-}O−ion has comparatively larger size than oxygen atom

  3. C

    O−\mathrm{O}^{-}O−ion will tend to resist the addition of another electron

  4. D

    Oxygen has high electron affinity

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