The blood red color obtained in the detection of nitrogen and sulphur together in an organic compound in Lassaigne's test is due to

Options

A. `[Fe(CNS)]^(+)`
B. `[Fe(SCN)_(2)]^(+)`
C. `[Fe(CNS)_(3)]^(-)`
D. `[Fe(CNS)_(2)]^(2+)`

Answer

To solve the question regarding the blood red color obtained in the detection of nitrogen and sulfur together in an organic compound in Lassaigne's test, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Lassaigne's Test:**
- Lassaigne's test is a qualitative analysis method used to detect the presence of certain elements in organic compounds, specifically nitrogen, sulfur, phosphorus, and halogens.

2. **Reaction with Sodium:**
- In this test, the organic compound is heated with sodium metal. This process converts the nitrogen and sulfur present in the organic compound into soluble sodium salts (sodium cyanide for nitrogen and sodium sulfide for sulfur).

3. **Formation of Lassaigne's Filtrate:**
- After the reaction, the mixture is cooled and then treated with water. The soluble components are dissolved, and the resulting solution is filtered to obtain the Lassaigne's filtrate.

4. **Adding Ferric Chloride:**
- To detect the presence of nitrogen and sulfur, ferric chloride (FeCl₃) is added to the Lassaigne's filtrate.

5. **Formation of Blood Red Color:**
- The blood red color observed in the solution is due to the formation of a complex between ferric ions (Fe³⁺) and thiocyanate ions (SCN⁻), which is produced when both nitrogen (as cyanide) and sulfur (as sulfide) are present in the filtrate. The complex formed is known as ferric thiocyanate (Fe(SCN)₃), which exhibits a characteristic blood red color.

6. **Conclusion:**
- Therefore, the blood red color obtained in the detection of nitrogen and sulfur together in an organic compound in Lassaigne's test is due to the formation of ferric thiocyanate.

### Final Answer:
The blood red color obtained in the detection of nitrogen and sulfur together in an organic compound in Lassaigne's test is due to the formation of ferric thiocyanate (Fe(SCN)₃).

---