Phosphine is obtained when
I. white P is heated with NaOH.
II. `Ca_3P_2` reacts with water.
III. Phosphorus trioxide is boiled with water.
The above mentioned correct statement(s) is`//` are

Options

A. I and III
B. II and III
C. Only III
D. All of the above

Answer

To determine which statements are correct regarding the preparation of phosphine (PH₃), we will analyze each statement one by one.

### Step 1: Analyze Statement I
**Statement I:** White phosphorus is heated with NaOH.

- **Reaction:** When white phosphorus (P₄) is heated with sodium hydroxide (NaOH), the reaction can be represented as:
\[ P_4 + 4NaOH + 2H_2O \rightarrow 2Na_2HPO_2 + 2PH_3 \]
- **Products:** The products include phosphine (PH₃) and sodium hypophosphite (Na₂HPO₂). Thus, this statement is correct.

### Step 2: Analyze Statement II
**Statement II:** Calcium phosphide (Ca₃P₂) reacts with water.

- **Reaction:** The reaction of calcium phosphide with water can be represented as:
\[ Ca_3P_2 + 6H_2O \rightarrow 3Ca(OH)_2 + 2PH_3 \]
- **Products:** This reaction produces phosphine (PH₃) and calcium hydroxide (Ca(OH)₂). Therefore, this statement is also correct.

### Step 3: Analyze Statement III
**Statement III:** Phosphorus trioxide (P₂O₃) is boiled with water.

- **Reaction:** When phosphorus trioxide is boiled with water, the reaction can be represented as:
\[ P_2O_3 + 3H_2O \rightarrow 2H_3PO_3 + PH_3 \]
- **Products:** This reaction yields phosphine (PH₃) along with orthophosphoric acid (H₃PO₃). Thus, this statement is correct as well.

### Conclusion
Since all three statements are correct, we conclude that phosphine can be obtained from all the mentioned reactions.

**Final Answer:** All of the above statements (I, II, and III) are correct.

---