Which of the following species is paramagnetic

Options

A. A carbonium ion
B. A free radical
C. A carbanion
D. All of these

Answer

To determine which species is paramagnetic among the given options (carbonium ion, free radical carbon ion, or all of these), we need to analyze the electron configurations of each species.

### Step-by-Step Solution:

1. **Understand Paramagnetism**:
- Paramagnetic species have unpaired electrons. If a species has one or more unpaired electrons, it will be attracted to a magnetic field.

2. **Analyze the Carbonium Ion (Cation)**:
- The carbonium ion (e.g., CH3^+) has a positive charge, which indicates that it has lost an electron.
- In CH3^+, carbon has 6 electrons (4 from carbon and 3 from the three hydrogens).
- The electron configuration shows that all electrons are paired. Therefore, the carbonium ion is **diamagnetic** (not paramagnetic).

3. **Analyze the Free Radical Carbon Ion**:
- A free radical carbon ion (e.g., CH3·) has an unpaired electron.
- In CH3·, carbon has 7 electrons (4 from carbon and 3 from the three hydrogens).
- The electron configuration shows that there is one unpaired electron. Therefore, the free radical carbon ion is **paramagnetic**.

4. **Analyze the Carbanion**:
- The carbanion (e.g., CH3^-) has an extra electron due to the negative charge.
- In CH3^-, carbon has 8 electrons (4 from carbon and 3 from the three hydrogens, plus 1 extra electron).
- The electron configuration shows that all electrons are paired. Therefore, the carbanion is **diamagnetic**.

5. **Conclusion**:
- Among the species analyzed, only the free radical carbon ion has unpaired electrons and is therefore paramagnetic.
- The answer to the question is that the **free radical carbon ion is paramagnetic**.

### Final Answer:
The species that is paramagnetic is the **free radical carbon ion**.

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