`AlF_(3)` soluble in `HF` only in presence of KF. It is due to the formation of

Options

A. `K_(3)[AlF_(3)H_(3)]`
B. `K_(3)[AlF_(6)]`
C. `AlH_(3)`
D. `Kl[AlF_(3)H]`

Explanation

To solve the question regarding the solubility of AlF₃ in HF only in the presence of KF, we can break down the explanation step by step.

### Step-by-Step Solution:

1. **Understanding AlF₃ Solubility**:
- AlF₃ (aluminum fluoride) is generally insoluble in water and many solvents. However, it shows solubility in hydrofluoric acid (HF) under certain conditions.

2. **Role of HF**:
- In anhydrous HF, AlF₃ can dissolve, but the solubility is limited because the fluoride ions (F⁻) are not freely available due to hydrogen bonding in HF. The HF molecules form hydrogen bonds, which reduces the availability of F⁻ ions.

3. **Introduction of KF**:
- When KF (potassium fluoride) is added to the system, it provides additional fluoride ions (F⁻) that can interact with AlF₃.

4. **Formation of Complex**:
- The presence of KF leads to the formation of a complex ion. Specifically, the fluoride ions from KF can react with AlF₃ to form the complex K₃AlF₆ (potassium hexafluoroaluminate).
- The reaction can be summarized as:
\[ AlF_3 + 3KF \rightarrow K_3AlF_6 \]
- This complex is soluble in HF, which explains why AlF₃ becomes soluble in HF only when KF is present.

5. **Conclusion**:
- Therefore, the solubility of AlF₃ in HF in the presence of KF is due to the formation of the complex K₃AlF₆.

### Final Answer:
AlF₃ is soluble in HF only in the presence of KF due to the formation of the complex K₃AlF₆.

---