Phosphine is not obtained by which of the following reaction?

Options

A. White P is heated witch conc. NaOH in an inert atmosphere of `CO_2`
B. Calcium phosphide treated with water
C. Phosphonium iodide treated with KOH
D. `PCl_5` treated with water

Answer

To solve the question "Phosphine is not obtained by which of the following reactions?", we will analyze each option provided and determine whether phosphine (PH₃) is produced in the reaction.

### Step-by-Step Solution:

1. **Option 1: White phosphorus (P₄) heated with concentrated NaOH in an inert atmosphere of carbon dioxide.**
- Reaction: P₄ + NaOH + H₂O → PH₃ + NaH₂PO₂
- In this reaction, phosphine (PH₃) is produced along with sodium hypophosphite (NaH₂PO₂).
- **Conclusion:** Phosphine is obtained.

2. **Option 2: Calcium phosphate (Ca₃(PO₄)₂) reacts with water.**
- Reaction: Ca₃(PO₄)₂ + H₂O → PH₃ + Ca(OH)₂
- In this reaction, phosphine (PH₃) is produced along with calcium hydroxide (Ca(OH)₂).
- **Conclusion:** Phosphine is obtained.

3. **Option 3: Phosphonium iodide (PH₄I) reacts with potassium hydroxide (KOH).**
- Reaction: PH₄I + KOH → PH₃ + KI + H₂O
- In this reaction, phosphine (PH₃) is produced along with potassium iodide (KI) and water.
- **Conclusion:** Phosphine is obtained.

4. **Option 4: Phosphorus pentachloride (PCl₅) reacts with water.**
- Reaction: PCl₅ + H₂O → POCl₃ + HCl
- In this reaction, phosphorus pentachloride reacts with water to produce phosphorus oxychloride (POCl₃) and hydrochloric acid (HCl).
- **Conclusion:** Phosphine is **not** obtained.

### Final Answer:
Phosphine is not obtained by the reaction of phosphorus pentachloride (PCl₅) with water.