Which of the following is paramagnetic

Options

A. `O_2^(+)`
B. `CN^(-)`
C. `CO`
D. `N_2`

Explanation

To determine which of the given species is paramagnetic, we need to analyze the electron configurations of the options provided. Paramagnetic substances have unpaired electrons, while diamagnetic substances have all paired electrons.

### Step-by-step Solution:

1. **Understanding Paramagnetism**:
- Paramagnetic substances have unpaired electrons in their atomic or molecular orbitals.
- Diamagnetic substances have all electrons paired.

2. **Counting Electrons**:
- We need to find the total number of electrons in each species provided in the options.

3. **Analyzing Each Species**:
- **O2**: Oxygen has 8 electrons. Therefore, O2 has 16 electrons. In the O2 molecule, the electronic configuration is:
- σ1s² σ*1s² σ2s² σ*2s² σ2p² (2 unpaired electrons in the π* orbitals) → **Paramagnetic**.
- **O2⁻**: This species has one additional electron compared to O2. Thus, it has 17 electrons. The configuration will have one more electron in the π* orbital:
- σ1s² σ*1s² σ2s² σ*2s² σ2p² π*2px² (2 unpaired electrons in the π* orbitals) → **Paramagnetic**.
- **N2**: Nitrogen has 7 electrons. Therefore, N2 has 14 electrons. The electronic configuration is:
- σ1s² σ*1s² σ2s² σ*2s² σ2p² (all paired) → **Diamagnetic**.
- **CO**: Carbon has 6 electrons and oxygen has 8 electrons, giving CO a total of 14 electrons. The electronic configuration is similar to N2:
- σ1s² σ*1s² σ2s² σ*2s² σ2p² (all paired) → **Diamagnetic**.
- **CN⁻**: Carbon has 6 electrons and nitrogen has 7 electrons, plus one extra electron due to the negative charge, giving a total of 14 electrons. The configuration is:
- σ1s² σ*1s² σ2s² σ*2s² σ2p² (all paired) → **Diamagnetic**.

4. **Conclusion**:
- The only species that is paramagnetic among the options is **O2** and **O2⁻** due to the presence of unpaired electrons.

### Final Answer:
The paramagnetic species is **O2** and **O2⁻**.