Among the following allotropic forms of sulphur , the number of allotropic forms , which will show paramagnetism is _________
(A) `alpha`-sulphur (B) `beta`-sulphur (C) `S_2`- form

Answer

To determine how many allotropic forms of sulfur exhibit paramagnetism, we will analyze each option given in the question: alpha-sulfur, beta-sulfur, and S2 form.

### Step-by-Step Solution:

1. **Understanding Allotropes of Sulfur**:
- Sulfur exists in several allotropic forms. The most common allotropes are alpha-sulfur (α-sulfur) and beta-sulfur (β-sulfur), which are both solid forms of sulfur. Additionally, there is the diatomic sulfur (S2) which exists in the vapor phase.

2. **Analyzing Alpha-Sulfur (α-sulfur)**:
- Alpha-sulfur is the most stable form of sulfur at room temperature and consists of a crown-shaped molecule with a specific arrangement of sulfur atoms.
- It has a complete electron pairing in its molecular structure, which means it does not have any unpaired electrons.
- **Conclusion**: Alpha-sulfur is **diamagnetic**.

3. **Analyzing Beta-Sulfur (β-sulfur)**:
- Beta-sulfur is another allotrope of sulfur that has a different crystalline structure compared to alpha-sulfur.
- Similar to alpha-sulfur, beta-sulfur also has all its electrons paired in its molecular structure.
- **Conclusion**: Beta-sulfur is **diamagnetic**.

4. **Analyzing Diatomic Sulfur (S2)**:
- The S2 molecule consists of two sulfur atoms. Each sulfur atom has 16 electrons, leading to a total of 32 electrons in the S2 molecule.
- When we look at the molecular orbital configuration for S2, we find that there are unpaired electrons present in the antibonding orbitals.
- Specifically, S2 has two unpaired electrons, which results in its paramagnetic nature.
- **Conclusion**: S2 is **paramagnetic**.

5. **Final Count of Paramagnetic Allotropes**:
- From our analysis, only the S2 form of sulfur shows paramagnetism, while both alpha-sulfur and beta-sulfur are diamagnetic.
- Therefore, the number of allotropic forms of sulfur that show paramagnetism is **1** (only S2).

### Final Answer:
The number of allotropic forms of sulfur that will show paramagnetism is **1**.

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