Sometimes a red colour is not produced in the Lassaigne's test even if both nitrogen and sulphur are present in the organic compound. Explain.

Explanation

To understand why a red color is not produced in Lassaigne's test even when both nitrogen and sulfur are present in an organic compound, we can break down the explanation into several steps:

### Step-by-Step Solution:

1. **Understanding Lassaigne's Test**:
- Lassaigne's test is used to detect the presence of nitrogen and sulfur in organic compounds. When an organic compound containing nitrogen and sulfur is fused with sodium metal, sodium thiocyanate (NaCNS) is formed.

2. **Formation of Sodium Thiocyanate**:
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