Which species does not exhibits paramagnetism:

Options

A. `N_(2)^(+)`
B. `O_(2)^(-)`
C. `CO`
D. `NO`

Answer

To determine which species does not exhibit paramagnetism, we need to analyze the electronic configurations of the given species and identify the presence of unpaired electrons. Paramagnetism occurs in species that have one or more unpaired electrons.

### Step-by-Step Solution:

1. **Understand Paramagnetism**:
- Paramagnetism is exhibited by species that have unpaired electrons. If all electrons are paired, the species will be diamagnetic and will not exhibit paramagnetism.

2. **Analyze Each Species**:
- We will analyze the electronic configurations of the given species one by one.

3. **Species A: N2+**:
- Nitrogen (N) has an atomic number of 7. Therefore, N2 has a total of 14 electrons (7 from each nitrogen).
- For N2+, we remove one electron, resulting in 13 electrons.
- The electronic configuration for N2+ is:
- σ1s² σ*1s² σ2s² σ*2s² σ2p² (with one electron in the 2p orbital).
- There is 1 unpaired electron in the 2p orbital, so N2+ exhibits paramagnetism.

4. **Species B: O2-**:
- Oxygen (O) has an atomic number of 8. Therefore, O2 has a total of 16 electrons (8 from each oxygen).
- For O2-, we add one electron, resulting in 17 electrons.
- The electronic configuration for O2- is:
- σ1s² σ*1s² σ2s² σ*2s² σ2p² (with one unpaired electron in the 2p orbital).
- There is 1 unpaired electron, so O2- exhibits paramagnetism.

5. **Species C: CO (Carbon Monoxide)**:
- Carbon (C) has an atomic number of 6 and Oxygen (O) has an atomic number of 8. Therefore, CO has a total of 14 electrons (6 from carbon and 8 from oxygen).
- The electronic configuration for CO is:
- σ1s² σ*1s² σ2s² σ*2s² σ2p² (with all electrons paired).
- All electrons are paired, so CO does not exhibit paramagnetism (it is diamagnetic).

6. **Species D: NO (Nitric Oxide)**:
- Nitrogen (N) has an atomic number of 7 and Oxygen (O) has an atomic number of 8. Therefore, NO has a total of 15 electrons (7 from nitrogen and 8 from oxygen).
- The electronic configuration for NO is:
- σ1s² σ*1s² σ2s² σ*2s² σ2p² (with one unpaired electron in the 2p orbital).
- There is 1 unpaired electron, so NO exhibits paramagnetism.

### Conclusion:
The species that does not exhibit paramagnetism is **C: CO (Carbon Monoxide)**, as it has all paired electrons.