Lassaigne's test is used for th detection of:

Options

A. `N,S`, halogens
B. C, H, and P
C. C, H, and O
D. C, S, and P

Explanation

**Step-by-Step Solution:**

1. **Understanding Lassaigne's Test**: Lassaigne's test is a qualitative analysis method used to detect certain elements in organic compounds. It is particularly useful for identifying nitrogen, sulfur, and halogens.

2. **Identifying the Elements Detected**:
- **Nitrogen**: Lassaigne's test can detect nitrogen by forming sodium cyanide when the organic compound is fused with sodium metal.
- **Sulfur**: Sulfur can be detected as sodium sulfide in the test.
- **Halogens**: Halogens (like chlorine, bromine, and iodine) can also be detected through the formation of sodium halides.

3. **Evaluating the Options**:
- **Option 1**: Nitrogen, Sulfur, and Halogens - This option is correct as all these elements can be detected using Lassaigne's test.
- **Option 2**: Carbon, Hydrogen, and Phosphorus - This option is incorrect. Carbon and hydrogen are not detected using Lassaigne's test; instead, they are typically analyzed by combustion methods.
- **Option 3**: Carbon, Hydrogen, and Oxygen - This option is also incorrect for the same reasons as option 2.
- **Option 4**: Carbon, Sulfur, and Phosphorus - This option is incorrect because while sulfur can be detected, carbon cannot be detected using Lassaigne's test.

4. **Conclusion**: The only correct option that lists elements detected by Lassaigne's test is the first one: Nitrogen, Sulfur, and Halogens.

**Final Answer**: Lassaigne's test is used for the detection of Nitrogen, Sulfur, and Halogens.

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