Reagent used to reduce `NO_(3)^(-)` to `NH_(3)`

Options

A. Devarda's alloy
B. Permanganate
C. German silver
D. Aluminum bronze

Answer

To determine the reagent used to reduce \( \text{NO}_3^- \) (nitrate ion) to \( \text{NH}_3 \) (ammonia), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reduction Reaction**:
- The reduction of nitrate ions (\( \text{NO}_3^- \)) to ammonia (\( \text{NH}_3 \)) involves the gain of electrons and a decrease in oxidation state.

2. **Consider Possible Reagents**:
- We have several options to consider:
- **Devarda's Alloy**
- **Permanent**
- **German Silver**
- **Aluminium Bronze**

3. **Research on Devarda's Alloy**:
- Devarda's alloy is composed of aluminum, zinc, and copper. It is known for its ability to reduce nitrates to ammonia.

4. **Chemical Reaction**:
- A typical reaction using Devarda's alloy can be represented as follows:
\[ 3 \text{NO}_3^- + 8 \text{Al} + 5 \text{OH}^- + 18 \text{H}_2\text{O} \rightarrow 3 \text{NH}_3 + 8 \text{Al(OH)}_4^- \]
- In this reaction, aluminum acts as the reducing agent, facilitating the conversion of nitrate to ammonia.

5. **Conclusion**:
- Based on the reactions and the properties of the reagents, **Devarda's Alloy** is the most suitable option for reducing \( \text{NO}_3^- \) to \( \text{NH}_3 \).

### Final Answer:
The reagent used to reduce \( \text{NO}_3^- \) to \( \text{NH}_3 \) is **Devarda's Alloy**.

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