Correct option is (a) Nitrogen
Kjedahl's method is simpler and more convenient than Duma's method. This method is largely used for the estimation of nitrogen in food stuff, drugs, fertilisers and many other organic compounds. However, this method cannot be used for organic compounds containing nitrogen in the ring such as pyridine, quinoline and organic compounds containing nitro (-NO2) and diazo (-N = N-) groups.
