Verified Solution • 2025–26 Session moderate

QAIPM-2015-Ch-1204: NEET 2015 Chemistry - Class 12 AIPM-2015-Ch-1204 Solution: The formation of the oxide ion \(O^{2-}(g)\) from oxygen atom…

The formation of the oxide ion O2−(g)O^{2-}(g) from oxygen atom requires first an exothermic and then an endothermic step as shown below: O(g)+e−→O−(g);ΔfH∘=−141 kJ mol−1O(g) + e^- \rightarrow O^-(g); \Delta_f H^\circ = -141\ \text{kJ mol}^{-1} O−(g)+e−→O2−(g);ΔfH∘=+780 kJ mol−1O^-(g) + e^- \rightarrow O^{2-}(g); \Delta_f H^\circ = +780\ \text{kJ mol}^{-1} Thus process of formation of O2−O^{2-} is isoelectronic with neon. It is due to the fact that O−O^- ion has comparatively smaller size than oxygen atom oxygen is more electronegative addition of electron in oxygen results in larger size of the ion electron repulsion outweighs the stability gained by achieving noble gas configuration.

Multiple Choice Options

  • A O −- _ ion has comparatively smaller size than oxygen atom
  • B oxygen is more electronegative
  • C addition of electron in oxygen results in larger size of the ion
  • D electron repulsion outweighs the stability gained by achieving noble gas configuration.

Step-by-Step Verified Solution

Comprehensive step-by-step solution and verified mathematical derivation available.

Related Learning Resources & Exam Preparation

NEET PYQ Question Bank
Browse year-wise authentic previous years' questions with solutions
Authentic CBT Mock Tests
Simulate official exam environment with live timer and percentile scoring