Question

Compound that will give positive Lassaigne’s test for both nitrogen and halogen is

• A. CH₃NH₂.HCl
• B. NH₂OH .HCl
• C. NH₄Cl
• D. N₂H₄ . HCl

Hint:

For Lassaigne’s test:
• Organic compounds must contain nitrogen or halogens for detection.
• Both nitrogen and halogen must be part of the same compound to test positive for both.

Answer 1

The Correct Option is A

1. Lassaigne’s Test: This test detects nitrogen, sulfur, and halogens in organic compounds.
- The compound is fused with sodium, converting nitrogen into NaCN and halogen into NaX (\(X = \text{Cl, Br, I}\)).
2. Compound Analysis:
  \(\text{N}_2\text{H}_4\cdot\text{HCl}\): Contains nitrogen but no halogen.
   \(\text{CH}_3\text{NH}_2\cdot\text{HCl}\): Contains both nitrogen (from the \(-\text{NH}_2\) group) and halogen (\(\text{Cl}\) from \(\text{HCl}\)).
\(\text{NH}_4\text{Cl}\): Contains nitrogen and halogen but is not an organic compound.
   \(\text{NH}_2\text{OH}\cdot\text{HCl}\): Contains nitrogen and halogen but does not form the required products in Lassaigne’s test.
3. Conclusion: Only \(\text{CH}_3\text{NH}_2\cdot\text{HCl}\) gives a positive Lassaigne’s test for both nitrogen and halogen.
Final Answer: (2) \(\text{CH}_3\text{NH}_2\cdot\text{HCl}\).