Spin isomerism is shown by

Options

A. Dichloro benzene
B. Hydrogen
C. Dibasic acid
D. n-butane

Answer

To solve the question regarding which compound exhibits spin isomerism, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Spin Isomerism**:
- Spin isomerism is a type of isomerism that arises due to the different orientations of nuclear spins in molecules. In the case of hydrogen, it specifically refers to the two forms of dihydrogen (H₂): ortho hydrogen and para hydrogen.

2. **Identifying the Forms of Hydrogen**:
- **Ortho Hydrogen**: This form occurs when the two hydrogen nuclei (protons) have their spins aligned in the same direction. This results in a total nuclear spin of 1.
- **Para Hydrogen**: This form occurs when the spins of the two hydrogen nuclei are opposite, leading to a total nuclear spin of 0.

3. **Analyzing the Options**:
- **Dichlorobenzene**: This compound does not exhibit spin isomerism as it does not have hydrogen atoms in the context of nuclear spin.
- **Hydrogen (H₂)**: As discussed, H₂ can exist in two spin states (ortho and para), thus it shows spin isomerism.
- **Dibasic Acid**: This compound does not exhibit spin isomerism as it does not have the necessary nuclear spin configurations.
- **Butane**: This is a hydrocarbon that does not exhibit spin isomerism since it does not have the same nuclear spin characteristics as dihydrogen.

4. **Conclusion**:
- Based on the analysis, the only compound that shows spin isomerism is **Hydrogen (H₂)**.

### Final Answer:
The correct option is **Hydrogen**.

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