With which of the following metal dil. `HNO_3` produces nitrous oxide ?

Options

A. Ag
B. Zn
C. Cu
D. Fe

Answer

To determine which metal reacts with dilute HNO3 to produce nitrous oxide (N2O), we can analyze the reactions of the given metals with dilute nitric acid.

### Step-by-Step Solution:

1. **Identify the Metals**: The metals provided in the question are typically silver (Ag), zinc (Zn), copper (Cu), and iron (Fe).

2. **Reactions with Dilute HNO3**:
- **Silver (Ag)**:
- Reaction:
\[ 3Ag + 4HNO_3 \rightarrow 3AgNO_3 + 2H_2O + NO \]
- Products: Silver nitrate, water, and nitrogen monoxide (NO).
- Conclusion: No nitrous oxide (N2O) is produced.

- **Zinc (Zn)**:
- Reaction:
\[ 4Zn + 10HNO_3 \rightarrow 4Zn(NO_3)_2 + 5H_2O + N_2O \]
- Products: Zinc nitrate, water, and nitrous oxide (N2O).
- Conclusion: Nitrous oxide is produced.

- **Copper (Cu)**:
- Reaction:
\[ Cu + 4HNO_3 \rightarrow Cu(NO_3)_2 + 2H_2O + 2NO \]
- Products: Copper nitrate, water, and nitrogen monoxide (NO).
- Conclusion: No nitrous oxide (N2O) is produced.

- **Iron (Fe)**:
- Reaction:
\[ 4Fe + 10HNO_3 \rightarrow 4Fe(NO_3)_2 + 5H_2O + NH_4NO_3 \]
- Products: Iron nitrate, water, and ammonium nitrate.
- Conclusion: No nitrous oxide (N2O) is produced.

3. **Conclusion**: Based on the reactions analyzed, only zinc (Zn) produces nitrous oxide (N2O) when reacted with dilute HNO3.

### Final Answer:
The metal that produces nitrous oxide (N2O) when reacting with dilute HNO3 is **Zinc (Zn)**.

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