Which of the following halides of group 15 is not hydrolysed ?

Options

A. `NF_3 `
B. `NI_3 `
C. `PF_3 `
D. Both (1) & (3)

Answer

To determine which halides of group 15 are not hydrolyzed, we will analyze the halides mentioned in the question. The halides of group 15 include NF3 (Nitrogen trifluoride), PF3 (Phosphorus trifluoride), and potentially others.

### Step-by-Step Solution:

1. **Identify the Halides**: The halides of group 15 we are considering are NF3 and PF3.

2. **Understand Hydrolysis**: Hydrolysis refers to the reaction of a compound with water, which can lead to the breakdown of the compound. For a compound to undergo hydrolysis, it typically needs to have available orbitals for water to attack.

3. **Analyze NF3**:
- NF3 consists of nitrogen (N) and fluorine (F).
- Nitrogen is in the second period of the periodic table and does not have d orbitals available for bonding or expansion of its octet.
- The absence of vacant d orbitals means that water cannot effectively attack NF3, leading to the conclusion that NF3 does not hydrolyze.

4. **Analyze PF3**:
- PF3 consists of phosphorus (P) and fluorine (F).
- Phosphorus is in the third period and has vacant d orbitals available.
- However, the bond between phosphorus and fluorine (P-F) is stronger than the bond that would form between phosphorus and hydroxide (P-OH). This strong bond makes it difficult for water to replace the fluorine atoms, thus PF3 also does not hydrolyze.

5. **Conclusion**: Based on the analysis, both NF3 and PF3 do not undergo hydrolysis. Therefore, the correct answer is that both NF3 and PF3 are not hydrolyzed.

### Final Answer:
The halides of group 15 that are not hydrolyzed are NF3 and PF3.