Freshly prepared solution of sodium nitroprusside is added to the sodium extract. Appearance of a deep violet colour indicates the presence of

Options

A. nitrogen
B. sulphur
C. both nitrogenn and sulphur
D. halogen

Explanation

To solve the question regarding the appearance of a deep violet color when freshly prepared sodium nitroprusside is added to a sodium extract, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Sodium Extract**:
- A sodium extract is prepared by heating sodium metal with a sample, which can contain various elements. The sample is fused with sodium, and upon heating, it reacts to form sodium compounds.

2. **Formation of Sodium Sulphide**:
- When sulfur is present in the sample, it reacts with sodium to form sodium sulfide (Na2S). The reaction can be represented as:
\[ 2Na + S \rightarrow Na2S \]

3. **Sodium Nitroprusside Test**:
- The sodium nitroprusside test is specifically used to detect the presence of sulfide ions (S²⁻) in the sodium extract. When sodium nitroprusside (Na2[Fe(CN)5NO]) is added to the sodium extract containing sodium sulfide, a characteristic deep violet color is produced.

4. **Chemical Reaction**:
- The reaction that occurs when sodium nitroprusside is added to sodium sulfide can be represented as:
\[ Na2S + Na2[Fe(CN)5NO] \rightarrow Na4[Fe(CN)5NOS] + 2NaOH \]
- This reaction leads to the formation of a complex that imparts a deep violet color.

5. **Conclusion**:
- The appearance of a deep violet color indicates the presence of sulfur in the sodium extract. Therefore, the correct answer to the question is sulfur.

### Final Answer:
The appearance of a deep violet color indicates the presence of **sulfur**.

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