Question:

Nitrogen can be estimated by Kjeldahl's method for which of the following compound?

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Kjeldahl's method fails for nitro, azo, azoxy compounds, ring nitrogen (pyridine) and diazonium salts; it works for amines.
Updated On: Nov 4, 2026
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The Correct Option is D

Solution and Explanation

Kjeldahl's method converts N in the compound to \(\mathrm{(NH_4)_2SO_4}\) on digestion with conc. \(\mathrm{H_2SO_4}\). It is not applicable to compounds containing nitro or azo groups, nitrogen in the ring (such as pyridine), or diazonium salts, because their nitrogen is not converted to ammonium sulphate.
Option (1) nitrobenzene: nitro group, not applicable. Option (2) pyridine: nitrogen in ring, not applicable. Option (3) benzenediazonium chloride: diazonium salt, not applicable. Option (4) benzylamine \(\mathrm{C_6H_5CH_2NH_2}\): amino nitrogen, converted to ammonium sulphate, so the method works.
Answer: (4) benzylamine, \(\mathrm{C_6H_5CH_2NH_2}\)
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