Phosphine is obtained by the reaction when

Options

A. White phophorus is heated with NaOH
B. `Ca_(3)P_(2)` reacts with water
C. red phosphorus is heated with NaOH
D. phosphorus is heated in current of hydrogen

Answer

To determine how phosphine (PH₃) is obtained, we can analyze the reactions provided in the question. Here’s a step-by-step breakdown:

### Step 1: Reaction of White Phosphorus with Sodium Hydroxide
1. **Identify the reactants**: White phosphorus (P₄) and sodium hydroxide (NaOH).
2. **Write the balanced chemical equation**:
\[ P_4 + 4 NaOH + 2 H_2O \rightarrow 2 PH_3 + 2 NaH_2PO_2 \]
In this reaction, white phosphorus reacts with sodium hydroxide and water to produce phosphine and sodium hypophosphate.

### Step 2: Reaction of Calcium Phosphide with Water
1. **Identify the reactants**: Calcium phosphide (Ca₃P₂) and water (H₂O).
2. **Write the balanced chemical equation**:
\[ Ca_3P_2 + 6 H_2O \rightarrow 2 PH_3 + 3 Ca(OH)_2 \]
Here, calcium phosphide reacts with water to produce phosphine and calcium hydroxide.

### Step 3: Reaction of Red Phosphorus with Sodium Hydroxide
1. **Identify the reactants**: Red phosphorus (P) and sodium hydroxide (NaOH).
2. **Evaluate the reaction**: Red phosphorus is less reactive than white phosphorus and does not react with sodium hydroxide to form phosphine. Thus, this statement is false.

### Step 4: Heating Phosphorus in a Current of Hydrogen
1. **Identify the reactants**: Phosphorus (P) and hydrogen (H₂).
2. **Evaluate the reaction**: There is no known reaction where phosphorus is heated in a current of hydrogen to produce phosphine. Therefore, this statement is also false.

### Conclusion
From the analysis, we conclude that:
- Phosphine is obtained from the reaction of white phosphorus with sodium hydroxide.
- Phosphine is also obtained from the reaction of calcium phosphide with water.
- The reactions involving red phosphorus and heating phosphorus in hydrogen do not yield phosphine.

### Final Answer
Phosphine is obtained by the reaction when:
1. White phosphorus is heated with sodium hydroxide.
2. Calcium phosphide reacts with water.