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. Addition of 6 M HCl produced no reaction. Addition of H2S with 0.2 M HCl produced a black solid. Addition of (NH4)2S produced a white solid. Addition of (NH4)2HPO4 in NH3 produced no reaction. 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.