Which of the following is not true of "concentration"?
a. it increases when you add more solute to the solvent.
b. it decreases when you add more solute to the solvent.
c. it decreases when you add more solvent to the solution.

The correct answer is B. The concentration of a solution does not decreases when you add more solute to the solvent. Instead, the concentration increases. Concentration is expressed as the amount of solute per unit of solvent. Therefore, increasing the solute, increases this value and increasing the solvent, decreases this value.