Since the moles of reactants are given and the equation is already balanced, we can tell that Ca(NO_{3})_{2} is the limiting reagent.

This is because the balanced equation tells us there is a 1:1 ratio of reactants to one another; 1 mole of K_{2}SO_{4 }reacts with 1 mole of Ca(NO_{3})_{2} to produce 1 mole of CaSO_{4} and 2 moles of KNO_{3}.

Since there are 5.00 moles of one reactant and 4.00 moles of the other, the greater number of moles will be present in excess and the smaller number is limiting. This would involve further calculation if the ratio of reactants were different.