Why is nitric acid added to sodium extract before adding silver nitrate for testing halogens?

Explanation

### Step-by-Step Solution:

1. **Understanding Sodium Extract**:
- Sodium extract, also known as Lassaigne's extract, is prepared by fusing an organic compound with sodium metal. This process helps in extracting halogens, nitrogen, and sulfur from the organic compound into a soluble form.

2. **Presence of Interfering Compounds**:
- In the sodium extract, halogens may be present along with other elements like nitrogen and sulfur. Specifically, sodium cyanide (NaCN) and sodium sulfide (Na2S) can also be formed during the extraction process.

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