Test (Q). A compound 'X' was fused with Na metal and the extract gave a white precipitate with `AgNO_(3)`. The Lassaigne's extract gave red colouration with neutral `FeCl_(3)`. Test R while compound 'Y' when fused with Na metal and subsequent analysis on its Lassaigne's extract did not give any characteristic test. Test S while compound Y on fusion with fusion mixture (sodium carbonate+potassium nitrate) or `Na_(2)O_(2)`, followed by extraction, followed by addition of conc. `HNO_(3)` and ammonium molybdate gave a yellow precipitate
Q. The chemical reaction taking place in Y, when it is fused with fusion mixture is

Options

A. `3Na+P+4O to Na_(3)PO_(4)`
B. `3Na_(2)CO_(3)+2P+[O] to 2Na_(3)PO_(4)+3CO_(2)`
C. `3KNO_(2)+P+3Oto K_(3)PO_(4)+3NO_(2)+O_(2)`
D. none of these

Answer

To solve the problem, we need to analyze the information provided in the question step by step and identify the chemical reaction that occurs when compound Y is fused with a fusion mixture.

### Step 1: Understanding the Tests
- **Test Q**: Compound X was fused with Na metal, resulting in a white precipitate with AgNO3 and a red coloration with neutral FeCl3. This indicates the presence of halides (likely Cl) and possibly nitrogen (indicated by the red coloration with FeCl3).

- **Test R**: Compound Y, when fused with Na metal, did not yield any characteristic tests in its Lassaigne's extract. This suggests that compound Y does not contain halides or nitrogen.

- **Test S**: Compound Y was fused with a fusion mixture of sodium carbonate and potassium nitrate (or Na2O2). The subsequent addition of concentrated HNO3 and ammonium molybdate produced a yellow precipitate, indicating the presence of phosphorus.

### Step 2: Identifying the Reaction in Test S
The fusion of compound Y with sodium carbonate and potassium nitrate suggests that phosphorus is being converted into a phosphate. The reaction can be represented as follows:

1. **Fusion Reaction**:
- Phosphorus reacts with sodium carbonate (Na2CO3) and oxygen from the air to form sodium phosphate (Na3PO4) and carbon dioxide (CO2).
- The balanced equation for this reaction is:
\[ 3 \text{Na}_2\text{CO}_3 + 2 \text{P} + \text{O}_2 \rightarrow 2 \text{Na}_3\text{PO}_4 + 3 \text{CO}_2 \]

### Step 3: Conclusion
The chemical reaction taking place in compound Y when it is fused with the fusion mixture is:
\[ 3 \text{Na}_2\text{CO}_3 + 2 \text{P} + \text{O}_2 \rightarrow 2 \text{Na}_3\text{PO}_4 + 3 \text{CO}_2 \]

### Final Answer
The correct option is:
**Option 2**: \( 3 \text{Na}_2\text{CO}_3 + 2 \text{P} + \text{O}_2 \rightarrow 2 \text{Na}_3\text{PO}_4 + 3 \text{CO}_2 \)

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