Which of the following halides cannot be hydrolysed?

Options

A. `TeF_(6)`
B. `SF_(6)`
C. `PCl_(5)`
D. `PCl_(3)`

Explanation

To determine which halide cannot be hydrolyzed, we will analyze each of the given compounds based on their chemical properties and behavior in the presence of water.

### Step-by-Step Solution:

1. **Identify the Compounds**:
Let's consider the halides mentioned in the question. We will analyze them one by one. The compounds are likely to include PCl3, PCl5, HF, and SF6.

2. **Analyze HF (Hydrofluoric Acid)**:
- HF is a hydrogen halide and can easily react with water.
- When HF is dissolved in water, it ionizes to form H⁺ and F⁻ ions.
- Therefore, HF can be hydrolyzed.

3. **Analyze PCl3 (Phosphorus Trichloride)**:
- PCl3 reacts with water to produce phosphorous acid (H3PO3) and hydrochloric acid (HCl).
- The reaction is as follows:
\[ \text{PCl}_3 + 3 \text{H}_2\text{O} \rightarrow \text{H}_3\text{PO}_3 + 3 \text{HCl} \]
- Thus, PCl3 can be hydrolyzed.

4. **Analyze PCl5 (Phosphorus Pentachloride)**:
- PCl5 also reacts with water, yielding phosphoric acid (H3PO4) and hydrochloric acid (HCl).
- The reaction is:
\[ \text{PCl}_5 + 4 \text{H}_2\text{O} \rightarrow \text{H}_3\text{PO}_4 + 5 \text{HCl} \]
- Therefore, PCl5 can also be hydrolyzed.

5. **Analyze SF6 (Sulfur Hexafluoride)**:
- SF6 is a stable compound and does not react with water.
- The compact size of sulfur in SF6 prevents the approach of water molecules, thus inhibiting hydrolysis.
- Therefore, SF6 cannot be hydrolyzed.

6. **Conclusion**:
- Among the compounds analyzed, only SF6 does not undergo hydrolysis when in contact with water.

### Final Answer:
The halide that cannot be hydrolyzed is **SF6**.