Consider the following: Benzene diazonium chloride, Nitrobenzene, Pyridine, Aniline, Benzylamine, urea. How many of the above compounds are not suitable for the estimation of nitrogen by Kjeldahl's method?
Show Hint
Kjeldahl method is NOT applicable to:
\[
-NO_2
\]
Nitro compounds,
Diazonium salts,
Many azo compounds,
Certain heterocyclic nitrogen compounds.
These are frequently asked exceptions in competitive examinations.