Which among the following are diamagnetic?

Options

A. `N_(2)`
B. `N^(2-)`
C. `O_(2)`
D. `O_(2)^(2-)`

Explanation

To determine which species among the given options are diamagnetic, we need to analyze the electron configurations of each species and check for the presence of unpaired electrons. A species is considered diamagnetic if it has no unpaired electrons, while it is paramagnetic if it has one or more unpaired electrons.

### Step-by-Step Solution:

1. **Understand the Concept of Diamagnetism and Paramagnetism**:
- Diamagnetic substances have all their electrons paired.
- Paramagnetic substances have one or more unpaired electrons.

2. **Analyze the Electron Configuration of N2**:
- N2 has 14 electrons.
- Its molecular orbital (MO) configuration is:
- σ1s², σ1s², σ2s², σ2s², π2px², π2py², σ2pz².
- All electrons are paired in this configuration.
- **Conclusion**: N2 is **diamagnetic**.

3. **Analyze the Electron Configuration of N2-**:
- N2- has 16 electrons (2 additional electrons).
- The configuration becomes:
- σ1s², σ1s², σ2s², σ2s², π2px², π2py², σ2pz², π*2px¹, π*2py¹.
- There are 2 unpaired electrons in the π* orbitals.
- **Conclusion**: N2- is **paramagnetic**.

4. **Analyze the Electron Configuration of O2**:
- O2 has 16 electrons.
- Its MO configuration is:
- σ1s², σ1s², σ2s², σ2s², σ2pz², π2px², π2py², π*2px¹, π*2py¹.
- There are 2 unpaired electrons in the π* orbitals.
- **Conclusion**: O2 is **paramagnetic**.

5. **Analyze the Electron Configuration of O2 2-**:
- O2 2- has 18 electrons (2 additional electrons).
- The configuration becomes:
- σ1s², σ1s², σ2s², σ2s², σ2pz², π2px², π2py², π*2px², π*2py².
- All electrons are paired in this configuration.
- **Conclusion**: O2 2- is **diamagnetic**.

### Final Conclusion:
Based on the analysis:
- N2 is **diamagnetic**.
- N2- is **paramagnetic**.
- O2 is **paramagnetic**.
- O2 2- is **diamagnetic**.

Thus, the species that are diamagnetic are **N2 and O2 2-**.