Three students, Manish Ramesh and Rajni were determining the extra elements present in an organic compound given by their teacher. They prepared the Lassaigne's extract (L.E.) independently by the fusion of the compound with sodium metal. Then they added solid `FeSO_(4)` and dilute sulphuric acid to a part of Lassaigne's extract. Manish and Rajni obtained prussian blue colour but Ramesh got red colour. Ramesh repeated the test with the same Lassaigne's extract, but again got red colour only. They were surprised and went to their teacher and told him about their observation. Teacher asked them to think over the reason for this. Can you help them by giving the reason for this. observation. Also, write the chemical equations to explain the formation of compounds of different colours.

Explanation

To understand the observations made by Manish, Ramesh, and Rajni, we need to analyze the results of their tests on the Lassaigne's extract (L.E.) and the reactions that occur when they add FeSO₄ and dilute sulfuric acid.

### Step-by-Step Solution:

1. **Preparation of Lassaigne's Extract**:
- The students prepared the Lassaigne's extract by fusing the organic compound with sodium metal. This process helps to convert any nitrogen, sulfur, or halogens present in the organic compound into their respective sodium salts.

2. **Testing with FeSO₄ and Dilute Sulfuric Acid**:
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