The qualitative analysis to the salt solution addition of reagents NH₄Cl +NH₄ OH and ammonium carbonate give precipitate in precipitate the oxidation state of anion (only magnitude) 

NH₄Cl +NH₄ OH used for detection of group III reagents. All cations of group III reagents are precipitate as hydroxides. When ammonium carbonate is added to NH₄Cl +NH₄ OH solution, then group IV cations are going to precipitate as carbonates, such as calcium carbonate (CaCO₃) and barium carbonate (BaCO³). In this, the anion is carbonate ion $\left({\mathrm{CO}}_3^{2-}\right)$ and its oxidation state is +2.