This one stumped me alot...

Aqueous solutions of a compound did not form precipitates with Cl-, Br-, I-, SO4 2-, CO3 2-, PO4 3-, OH-, or S 2-. This highly water-soluble compound produced the foul-smelling gas H2S when the solution was acidified. This compund is __?__.
a. Pb(NO3)2
b. (NH4)2S
c. KBr
d. Li2CO3
e. AgNO3

3 answers

In order to produce H2S, you MUST have a sulfide compound. You have only one listed. Can't be anything else. It also turns out that NH4X is soluble for that entire list you typed in which is a second check.

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(NH4)2S