Question

Which if the following compounds is insoluble in water

(NH4)2CO3
AgBr
CuSO4
KI
LiNO3

I thought it might be AgBr

Answer 1

Look at your solubility table (rules). Don't have one? Here is one on-line.
http://www.chem.vt.edu/RVGS/ACT/notes/solubility_rules.html