The formation of the oxide ion O2−(g) requires first an exothermic and then an endothermic step as shown below.O(g)+e−=O−(g);    ΔH∘=−142kJmol−1O−(g)+e−=O2−(g);    ΔH∘=844kJmol−1This is because

# The formation of the oxide ion ${\mathrm{O}}^{2-}\left(\mathrm{g}\right)$ requires first an exothermic and then an endothermic step as shown below.$\begin{array}{l}\mathrm{O}\left(\mathrm{g}\right)+{\mathrm{e}}^{-}={\mathrm{O}}^{-}\left(\mathrm{g}\right); \mathrm{\Delta }{H}^{\circ }=-142\mathrm{kJ}{\mathrm{mol}}^{-1}\\ {\mathrm{O}}^{-}\left(\mathrm{g}\right)+{\mathrm{e}}^{-}={\mathrm{O}}^{2-}\left(\mathrm{g}\right); \mathrm{\Delta }{H}^{\circ }=844\mathrm{kJ}{\mathrm{mol}}^{-1}\end{array}$This is because

1. A

oxygen is more electronegative

2. B

oxygen has high electron affinity

3. C

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

4. D

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

Fill Out the Form for Expert Academic Guidance!l

+91

Live ClassesBooksTest SeriesSelf Learning

Verify OTP Code (required)

### Solution:

The addition of negatively-charged electron to the negatively-charged species ${\mathrm{O}}^{-}$ requires an input of energy.

O− ion tends to resist the addition of another electron due to large repulsion of e−− e in small sized O− ion. Thus, energy is required to overcome this force of repulsion.

## Related content

 Consent Letter – How to Write Consent Letter with Format and Samples Sarvepalli Radhakrishnan Biography Relieving Letter Format, Samples and Templates for Employee How to Write Authorization Letter with Format, Samples and Tips Value of Legal Education in India – All You Need to Know 10 Ways that Education will Improve Your Life! 10 Time Management Tips to Use in Your Exam Preparation Letter to Principal with Format and Samples What is Next Test: National Exit Test – Details, Patterns, Eligibility What is Digital Literacy, Its Importance, and Challenges in Education?  +91

Live ClassesBooksTest SeriesSelf Learning

Verify OTP Code (required)