Which of the following do not undergo hydrolysis?

Options

A. `NCI_3`
B. `NF_3`
C. `PCI_3`
D. `PCI_5`

Answer

To determine which of the given compounds do not undergo hydrolysis, we will analyze each option: NCl3, NF3, PCl3, and PCl5.

### Step 1: Understand Hydrolysis
Hydrolysis is a chemical reaction involving the breaking of a bond in a molecule using water. In this process, water molecules react with the compound, leading to the formation of new products. Compounds that can undergo hydrolysis typically have the ability to accept hydroxide ions (OH-) or donate protons (H+).

### Step 2: Analyze Each Compound
1. **NCl3 (Nitrogen Trichloride)**: This compound can undergo hydrolysis as nitrogen can form bonds with hydroxide ions.

2. **NF3 (Nitrogen Trifluoride)**: This compound does not undergo hydrolysis. The reason is that nitrogen in NF3 does not have vacant d-orbitals to accommodate the hydroxide ions. Additionally, fluorine is highly electronegative, which makes nitrogen less reactive.

3. **PCl3 (Phosphorus Trichloride)**: This compound can undergo hydrolysis, reacting with water to form phosphorous acid (H3PO3) and hydrochloric acid (HCl).

4. **PCl5 (Phosphorus Pentachloride)**: This compound can also undergo hydrolysis to form phosphoric acid (H3PO4) and hydrochloric acid (HCl).

### Step 3: Conclusion
From the analysis, we find that:
- NCl3 undergoes hydrolysis.
- NF3 does not undergo hydrolysis.
- PCl3 undergoes hydrolysis.
- PCl5 undergoes hydrolysis.

Thus, the compound that does not undergo hydrolysis is **NF3**.

### Final Answer
**NF3 (Option B)** does not undergo hydrolysis.

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