How can I tell if the following equations produce precipitates or not?

Question

1. HgCl2 (aq) + K2CrO4 (aq) ==>
2. Ba(OH)2 (aq) + NaClO3 (aq) ==>
3. ZnI2 (aq) + CaSO4 (aq) ==>
4. SnCl2 (aq) + MgBr2 (aq) ==>

Answer 1

Here is a chart of solubility rules.
http://www.chem.vt.edu/RVGS/ACT/notes/solubility_rules.html