Q24 / 125 · BITSAT 2018 · Chemistry

Which of the following compound will give blood red colour while doing the Lassaigne's test for N.

  • A
    NH22C=O
  • Correct answer
    B

    H2NC6H4SO3H

  • C
    C6H5SO3H
  • D
    CHCl3

Solution

When nitrogen and sulphur both are present in the organic compound, they combine during fusion to form sodium thiocyanate (sulphocyanide).

Thus, the compounds containing both N and S give blood red colour in Lassaigne's test due to the formation of FeSCN2. Thus, H2NC6H4SO3H gives blood red colour in Lassaigne's test of nitrogen.

Hence, the correct answer is option: 'B'.

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