To determine which of the given species is diamagnetic, we need to analyze the electron configuration of each species using Molecular Orbital Theory (MOT). A diamagnetic molecule has all its electrons paired, while a paramagnetic molecule has unpaired electrons.
### Step-by-Step Solution:
1. **Identify the Species**: The question asks us to identify which among the given species is diamagnetic. Let's consider three common species: CO, O2, and B2.
2. **Count the Electrons**:
- **CO (Carbon Monoxide)**:
- Carbon (C) has 6 electrons.
- Oxygen (O) has 8 electrons.
- Total electrons in CO = 6 + 8 = 14 electrons.
- **O2 (Oxygen)**:
- Each oxygen atom has 8 electrons.
- Total electrons in O2 = 8 + 8 = 16 electrons.
- **B2 (Boron Dimer)**:
- Each boron atom has 5 electrons.
- Total electrons in B2 = 5 + 5 = 10 electrons.
3. **Fill the Molecular Orbitals**:
- **For CO (14 Electrons)**:
- The filling order based on MOT is:
- σ1s (2), σ1s* (2), σ2s (2), σ2s* (2), σ2p_z (2), π2p_x (2), π2p_y (2).
- All 14 electrons are filled, and there are no unpaired electrons. Thus, CO is **diamagnetic**.
- **For O2 (16 Electrons)**:
- The filling order is:
- σ1s (2), σ1s* (2), σ2s (2), σ2s* (2), σ2p_z (2), π2p_x (2), π2p_y (2), π2p_x* (1), π2p_y* (1).
- There are 2 unpaired electrons in the π2p_x* and π2p_y* orbitals. Thus, O2 is **paramagnetic**.
- **For B2 (10 Electrons)**:
- The filling order is:
- σ1s (2), σ1s* (2), σ2s (2), σ2s* (2), σ2p_z (2), π2p_x (1), π2p_y (1).
- There are 2 unpaired electrons in the π2p_x and π2p_y orbitals. Thus, B2 is **paramagnetic**.
4. **Conclusion**: Among CO, O2, and B2, the only species that is diamagnetic is **CO**.
### Summary:
- **Diamagnetic Species**: CO (Carbon Monoxide)
- **Paramagnetic Species**: O2 (Oxygen) and B2 (Boron Dimer)
