Chapter 5, Problem 76IAE

An unknown whitesolid consists of two compounds, each containing a different cation. As suggested in the illustration, the unknown is partially soluble in water. The solution is treated with NaOH(aq) and yields awhite precipitate. The part of the original solid that is insoluble in water dissolves in HCI(aq) with the evolution of a gas. The resulting solution is then treated with ${\left({\text{NH}}_{\text{4}}\right)}_{\text{2}}{\text{SO}}_{\text{4}}\left(\text{aq}\right)$ and yields white precipitate. (a) Is it possible that any of the cations ${\text{Mg}}^{\text{24}}{\text{, Cu}}^{\text{24}}{\text{, Ba}}^{\text{24}}{\text{, Na}}^{\text{4}}{\text{, or NH}}_{\text{4}}$ were present the original unknown? Explain your reasoning (b) what compounds could be in the unknown mixture (that is, what anions might be present)?