List of top Chemistry Questions on Analytical Chemistry asked in WBJEE

Which pair of ions among the following can be separated by precipitation method?

Kjeldahl's method cannot be used for the estimation of nitrogen in which compound?
 

(A)(B)(C)(D)
NH2-CH2-COOHC6H5-NH2C6H5-N=N-C6H5O2N-C6H4-NO2