To have a better understanding of what happens when two compounds are mixed together in aqueous solution, you should become familiar with the solubility rules
Usually, you are asked to determine whether or not a certain reaction will lead to the formation of a precipitate. In this case, you must work backwards - determine what reactants could be mixed starting from the product(s).
So, you're dealing with a double replacement reaction in which your cations and anions will exchange partners. You know that one of the products must be calcium carbonate,
You can use the solubility rules to help you pick a compound containing the
So, a soluble compound containing
When in aqueous solution, the complete ionic equation will be
If you remove spectator ions, i.e. the ions present on both sides of the equation, you'll get the net ionic equation
You can use the same approach to find other compounds soluble in aqueous solution that form a precipitate when they react, the reaction above is just one example.