Which of the following statements is not applicable to Lassaigne's test ?

Options

A. The extra elements (N,S and halogens) are tested as their inorganic salts.
B. During fusion of organic compound with sodium, `Na_(2)S,NaCN and N_(a)X` are formed.
C. It can even be used for the detection of hydrogen in the organic compound.
D. It is possible to differentiate between the different halogens.

Answer

### Step-by-Step Solution:

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

2. **Process of Lassaigne's Test**: The organic compound is fused with sodium metal. During this fusion, if nitrogen is present, sodium cyanide (NaCN) is formed. If sulfur is present, sodium sulfide (Na2S) is produced. If halogens are present, sodium halide (NaX) is formed.

3. **Analyzing the Options**:
- **Option A**: States that the extra elements (Nitrogen, Sulfur, and Halogens) are tested as their inorganic salts. This is applicable since we do form inorganic salts during the test.
- **Option B**: Mentions that during fusion, Na2S, NaCN, and NaX are formed. This is also applicable as it correctly describes the products formed during the test.
- **Option C**: Claims that Lassaigne's test can be used for the detection of hydrogen in the organic compound. This is **not applicable** because Lassaigne's test does not test for hydrogen; it is specifically for nitrogen, sulfur, and halogens.
- **Option D**: States that it is possible to differentiate between different halogens. This is applicable as different halogens can be distinguished based on the color of the precipitate formed when reacted with silver nitrate.

4. **Conclusion**: Since option C is not applicable to Lassaigne's test, it is the correct answer to the question.

### Final Answer:
**Option C** is the statement that is not applicable to Lassaigne's test.

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