`PH_(3)` can be obtained by:

Options

A. heating hypophosphorus acid
B. heating orthophosphorus aciid
C. reacting white phoshporus with hot conc. NaOH
D. hydrolysis of calcium phosphide

Answer

To determine how phosphine (PH₃) can be obtained, we can analyze the different methods mentioned in the video transcript step by step.

### Step 1: Heating Hypophosphorus Acid
- **Reaction**: When hypophosphorus acid (H₃PO₂) is heated at a temperature of about 50-140°C, it decomposes to form phosphine (PH₃) and phosphorous acid (H₃PO₃).
- **Balanced Equation**:
\[ 2 \, H_3PO_2 \rightarrow PH_3 + 3 \, H_3PO_3 \]
- **Conclusion**: This method is valid for obtaining phosphine.

### Step 2: Heating Orthophosphorus Acid
- **Reaction**: Heating orthophosphorus acid (H₃PO₃) leads to its decomposition into phosphine (PH₃) and orthophosphoric acid (H₃PO₄).
- **Balanced Equation**:
\[ 3 \, H_3PO_3 \rightarrow PH_3 + 4 \, H_3PO_4 \]
- **Conclusion**: This method is also valid for obtaining phosphine.

### Step 3: Reacting White Phosphorus with Hot Concentrated Sodium Hydroxide
- **Reaction**: When white phosphorus (P₄) reacts with hot concentrated sodium hydroxide (NaOH) in the presence of water, it produces phosphine (PH₃) and sodium hypophosphate (NaH₂PO₂).
- **Balanced Equation**:
\[ 3 \, P_4 + 3 \, NaOH + 3 \, H_2O \rightarrow 3 \, PH_3 + 3 \, NaH_2PO_2 \]
- **Conclusion**: This method is valid for obtaining phosphine.

### Step 4: Hydrolysis of Calcium Phosphide
- **Reaction**: Calcium phosphide (Ca₃P₂) reacts with water to produce phosphine (PH₃) and calcium hydroxide (Ca(OH)₂).
- **Balanced Equation**:
\[ Ca_3P_2 + 6 \, H_2O \rightarrow 2 \, PH_3 + 3 \, Ca(OH)_2 \]
- **Conclusion**: This method is also valid for obtaining phosphine.

### Final Conclusion
All four methods (A, B, C, and D) are valid for obtaining phosphine (PH₃).