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A specific organic compound successfully yields a deep Prussian blue coloration during Lassaigne's tQualitative and Quantitative Analysis Chemistry Question

Question

A specific organic compound successfully yields a deep Prussian blue coloration during Lassaigne's test for nitrogen. However, when subjected to Kjeldahl's digestion protocol, it completely fails to yield ammonium sulphate for quantitative estimation. The compound is most likely:

Answer: B

💡 Solution & Explanation

Azobenzene contains an azo group ($-N=N-$). While it possesses both C and N to form $NaCN$ during fusion (yielding a positive qualitative test), compounds with azo linkages strongly resist the reductive conversion to $NH_4^+$ required during Kjeldahl's acid digestion.

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