Kjeldahl's method is widely used for nitrogen estimation, but it fails for certain compounds. For wh — Qualitative and Quantitative Analysis Chemistry Question

💡 Solution & Explanation

Kjeldahl's method fails for compounds containing nitrogen in a nitro group ($-NO_2$), azo group ($-N=N-$), or within a heterocyclic ring (like pyridine), because the nitrogen in these structures cannot be quantitatively converted to ammonium sulphate during digestion.