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.

See explanation

Explanation:

If we look at the tests to be performed on the compounds carefully, we will notice that;

i) Addition of H2S with 0.2 M HCl produced a black solid. This black solid may result from the reaction;

H2S + Cu2+ >CuS(balck solid) + H2

or

H2S + Pb2+  >PbS(balck solid) + H2

Hence, Cu2+ or Pb2+  may be present

ii) Addition of (NH4)2S produced a white solid. This means that  K^+ may be present because the white precipitate is formed during metathesis.

iii) Potassium ion is known to burn with a purple flame.

Hence the suspected ions are;

Cu2+ , Pb2+ and  K^+

explanation: it gains negative electrons, therefore becoming negatively charged. as charge cannot be created, nor destroyed, only transferred, this leaves the wool positive. now that they have opposite charges, the two items attract.

it would be a gas formation