Fаilure tо fоllоw the instructions properly mаy void your exаm score. After you start the exam, make sure to note the timer. After the timer runs out, your exam will be submitted even if you didn't finish the exam. Good Luck! Periodic Table.png Link to a web version of the table that is compatible with screen reader technology: Periodic Table Solubility rules for ionic compounds A compound containing a cation from group 1 (alkali metal) or the ammonium ion (NH4+) is likely soluble. A compound containing an anion from group 17 (halides) is likely soluble. Exceptions: Ag+, Hg22+, and Pb2+ halides are insoluble. A compound containing nitrate (NO3-) or acetate (CH3CO2-) is likely soluble. A compound containing sulfate (SO42-) is likely soluble. Exceptions: Ba2+, Hg22+, and Pb2+ are insoluble. Any other ionic compounds are likely insoluble.