which of the following compounds does not form a precipitate when reacted with sodium hydroxide?
? feso4
? cu(no3)2
? fe(no3)3
? nano3

NaNO3

Explanation:

When you're dealing with the rules of solubility (Which compounds dissolve in water), there's a set of numbered rules you can follow.  You can find them in your textbook, but here's a short cut:

ANY, ANY, ANY compound that contains any of the following is soluble in water no mater what!

Na,  NO3,  NH4, K, ClO4, CH3COO

If you see sodium, nitrate, ammonium, perchlorate or acetate in the compound, it is soluble in water...