Which of the following compound is added to the sodium extract before addition of silver nitrate for testing of halogens?

Options

A. nitric acid
B. ammonia
C. hydrochloric acid
D. sodium hydroxide

Answer

To determine which compound is added to the sodium extract before the addition of silver nitrate (AgNO3) for testing halogens, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Context**:
- When testing for halogens in organic compounds, we first prepare a sodium extract. This involves treating the organic compound with sodium metal, which can lead to the formation of sodium halides, sodium cyanides, and sodium sulfides.

2. **Identifying the Problem**:
- The presence of nitrogen (from cyanides) and sulfur (from sulfides) in the sodium extract can interfere with the detection of halogens. Therefore, we need a way to eliminate these interfering substances.

3. **Adding a Compound**:
- To remove the nitrogen and sulfur from the sodium extract, we add a compound that can react with these components. The compound used for this purpose is **dilute nitric acid (HNO3)**.

4. **Reaction with Nitric Acid**:
- When dilute HNO3 is added to the sodium extract, it reacts with sodium cyanide (NaCN) to form sodium nitrate (NaNO3) and hydrogen cyanide (HCN). Similarly, it reacts with sodium sulfide (Na2S) to produce sodium nitrate and hydrogen sulfide (H2S).
- This reaction effectively removes the nitrogen and sulfur from the extract, leaving behind the halogens.

5. **Conclusion**:
- After the addition of dilute HNO3, the remaining sodium extract will primarily contain sodium halides. This allows for the subsequent addition of silver nitrate (AgNO3) to test for the presence of halogens, as the interference from nitrogen and sulfur has been eliminated.

### Final Answer:
The compound added to the sodium extract before the addition of silver nitrate for testing halogens is **dilute HNO3**.

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