[Iron Man]

Hello,

I`ve got some kind of quiz here, which my teacher has given to me:

There`s a substance A:
-with NaOH(aq)  there's a precipitate which can be solved in acids
-with BaCl2 there's a white precipitate which cannot be solved in acids
-in with NH3+H2O+H2S there will be some black solid
-with KSCN(aq) there wont be some colorful reaction

Out of reaction 2 I guess the Anion is the Sulfate-anion;
but I don't know what's the Kation.

Can somebody please help me?

[Borek]

Insoluble hydroxide, black sulfide, and definitely not the iron. See if anything mentioned here helps.