The LaSSaigen's extract is boiled with conc. `HNO_(3)` while testing for halogens. By doing so it `:`

Options

A. helps in the precipitation of AgCl
B. increases the solubility product of AgCl
C. increases the concentration of `NO_(3)^(-)` ions
D. decomposes `Na_(2)S` and NaCN , if formed

Explanation

To solve the question regarding the boiling of LaSSaigen's extract with concentrated HNO3 while testing for halogens, we can break down the process step by step:

### Step-by-Step Solution:

1. **Understanding the Purpose of the Test**:
The test is designed to identify the presence of halogens in the LaSSaigen's extract. Halogens include elements like chlorine, bromine, and iodine.

2. **Identifying Interfering Substances**:
The LaSSaigen's extract may contain sodium sulfide (Na2S) and sodium cyanide (NaCN). These substances can interfere with the halogen test by producing gases that complicate the results.

3. **Reaction with Concentrated HNO3**:
When the extract is boiled with concentrated nitric acid (HNO3), it reacts with sodium sulfide and sodium cyanide. The reactions are as follows:
- For sodium sulfide:
\[ 2 \text{Na}_2\text{S} + 6 \text{HNO}_3 \rightarrow 2 \text{NaNO}_3 + 3 \text{H}_2\text{S} \uparrow \]
- For sodium cyanide:
\[ 2 \text{NaCN} + 2 \text{HNO}_3 \rightarrow 2 \text{NaNO}_3 + \text{H}_2 + \text{C} \uparrow \]
In both reactions, hydrogen sulfide (H2S) and hydrogen cyanide (H2) gases are produced, which escape from the solution.

4. **Removing Interfering Compounds**:
By boiling the extract with concentrated HNO3, the sodium sulfide and sodium cyanide are decomposed into gases that can escape. This step is crucial as it cleans the extract of any potential contaminants that could affect the halogen test.

5. **Testing for Halogens**:
After the removal of interfering substances, the purified extract can be tested for halogens by adding silver nitrate (AgNO3). The presence of halogens will result in the formation of precipitates:
- Chlorine will produce a white precipitate (AgCl).
- Bromine will produce a yellow precipitate that dissolves in ammonia.
- Iodine will produce a yellow precipitate that is insoluble in ammonia.

6. **Conclusion**:
The main reason for boiling the LaSSaigen's extract with concentrated HNO3 is to decompose sodium sulfide and sodium cyanide, thereby preventing interference in the halogen testing process.

### Final Answer:
The correct answer is that boiling the LaSSaigen's extract with concentrated HNO3 is done to decompose sodium sulfide and sodium cyanide if they are present, which could interfere with the halogen test.

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