A solution contains some or all of the ions Cu2 , Al3 , K , Ca2 , Ba2 , Pb2 , and NH4 . The following tests were performed, in order, on the solution. 1. Addition of 6 M HCl produced no reaction.
2. Addition of H2S with 0.2 M HCl produced a black solid.
3. Addition of (NH4)2S produced a white solid.
4. Addition of (NH4)2HPO4 in NH3 produced no reaction.
5. The final supernatant when heated produced a purple flame.
Identify which of these ions were present in the solution, which were absent, and for which ones no conclusions can be drawn
a. Cu2+b. Al3+c. K+d. Ca2+e. Ba2+f. Pb2+g. NH4+.