Which of the following is diamagnetic ?

Options

A. `H_(2)^(+)`
B. `He_(2)^(+)`
C. `O_(2)`
D. `N_(2).`

Explanation

To determine which of the given species is diamagnetic, we will analyze the electron configurations of each species mentioned in the question. A species is considered diamagnetic if all of its electrons are paired, while it is paramagnetic if it has unpaired electrons.

### Step-by-Step Solution:

1. **Identify the Species**: The species we need to analyze are H2+, H2, O2, and N2.

2. **Analyze H2+**:
- **Number of Electrons**: H2+ has 1 electron (since it is a hydrogen molecule with a positive charge).
- **Electron Configuration**: The configuration is σ1s¹.
- **Unpaired Electrons**: There is 1 unpaired electron.
- **Conclusion**: H2+ is paramagnetic.

3. **Analyze H2**:
- **Number of Electrons**: H2 has 2 electrons.
- **Electron Configuration**: The configuration is σ1s².
- **Unpaired Electrons**: All electrons are paired.
- **Conclusion**: H2 is diamagnetic.

4. **Analyze O2**:
- **Number of Electrons**: O2 has 16 electrons.
- **Electron Configuration**: The configuration is σ1s² σ*1s² σ2s² σ*2s² σ2p² (with 2 unpaired electrons in the π* orbitals).
- **Unpaired Electrons**: There are 2 unpaired electrons.
- **Conclusion**: O2 is paramagnetic.

5. **Analyze N2**:
- **Number of Electrons**: N2 has 14 electrons.
- **Electron Configuration**: The configuration is σ1s² σ*1s² σ2s² σ*2s² (with 2 paired electrons in the σ2p and 4 paired electrons in the π2p orbitals).
- **Unpaired Electrons**: All electrons are paired.
- **Conclusion**: N2 is diamagnetic.

### Final Conclusion:
Among the species analyzed, H2 and N2 are diamagnetic. However, since the question asks for "which of the following is diamagnetic," the correct answer is **N2**.