For which of the following, Kjeldahl's method is not used for the estimation of nitrogen? I. Aniline II. Azobenzene III. Nitrobenzene IV. Pyridine

Step-by-step solution

Key Idea The groups in which nitrogen contain double bond or present in heterocyclic ring can not be estimated by Kjeldahl's method. aniline does not contain double bond, it can be estimated by Kjeldahl's method. (II) Azobenzene contain - N = N - group, thus does not estimated by Kjeldahl's method. (III) In nitrobenzene, nitrogen also contains estimated by Kjeldahl's method. (IV) Pyridine is a heterocyclic organic compound in which nitrogen is present in cyclic ring. Thus, it is also not estimated by Kjeldahl's met