Which of the following chloride does not react with `PCl_(5)` on heating?

Options

A. `Hg_(2)Cl_(2)`
B. `FeCl_(2)`
C. `S_(2)Cl_(2)`
D. `BC l_(3)`

Answer

To determine which chloride does not react with PCl5 upon heating, we need to analyze the oxidation states of the elements in the given chlorides and understand the behavior of PCl5 as an oxidizing agent.

### Step-by-Step Solution:

1. **Identify the Chlorides**: The chlorides we are considering are:
- Hg2Cl2 (Mercury(I) chloride)
- FeCl2 (Iron(II) chloride)
- S2Cl2 (Disulfur dichloride)
- BCl3 (Boron trichloride)

2. **Understand the Role of PCl5**: PCl5 acts as an oxidizing agent. This means it can oxidize other compounds while itself getting reduced.

3. **Calculate Oxidation States**:
- **Hg2Cl2**: Mercury (Hg) is in the +1 oxidation state. PCl5 can oxidize Hg from +1 to +2.
- **FeCl2**: Iron (Fe) is in the +2 oxidation state. PCl5 can oxidize Fe from +2 to +3.
- **S2Cl2**: Sulfur (S) is in the +1 oxidation state. PCl5 can oxidize S from +1 to +4.
- **BCl3**: Boron (B) is in the +3 oxidation state. This is the highest oxidation state for boron, meaning it cannot be oxidized further.

4. **Determine the Reaction**:
- Hg2Cl2, FeCl2, and S2Cl2 can all be oxidized by PCl5, meaning they will react.
- BCl3, however, is already in its highest oxidation state and cannot be oxidized further by PCl5.

5. **Conclusion**: Therefore, the chloride that does not react with PCl5 upon heating is **BCl3**.

### Final Answer:
**BCl3 does not react with PCl5 on heating.**

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