An aqueous solution of potassium carbonate combine with a solution of calcium nitrate.

what are the total and net ionic equation?

This is an example of a double replacement or precipitation reaction. The solutions of potassium carbonate and calcium nitrate both contain dissolved ions so they will appear as clear, colorless solutions. When the two solutions are combined the calcium ions will combine with the carbonate ions to form an insoluble precipitate, which will appear as a white cloudiness. Potassium ions and nitrate ions will remain dissolved in the solution. They're called "spectator ions" because they're present as both reactants and products - they don't participate in the chemical reaction. 

Solubility would be your answer.

Molarity is moles of solute over liters of solution. idk if that is what you are talking about, but you can convert moles of solute to grams of solute using dimensional analyzes by using molar mass found on the periodic table.