This is an interesting question from my exam. Basically, we add sugar into a solution when we need more concentrated solution and vice versa. Therefore, in order to choose what we will add (sugar or water), we must know if the solution was concentrated or not.
In chemistry, we know that case by percent mass, percent volume, ppm mass, ppm volume, molarity, molality, normality, and mole fraction. A solution with high percent/ppm mass/volume tends to be more concentrated. How about the others? They are same like percent mass/volume. So, don’t get confused. The only thing we must know is one of the magnitude above.
For example, if its molarity is less than the molarity of the solution which we need to prepare, then we must add the solute into the solution. If its molarity is more than the solution’s molarity we need, we must add the water (solvent).
