Which term describes solute concentration as moles per liter of solution?

• A. Molarity
• B. Molality
• C. Normality
• D. Density

Answer: (A)

Molarity describes solute concentration as moles per liter of solution. It is defined as the number of moles of solute divided by the volume of the solution in liters (M = n/V). This directly answers the question—the concentration is given in terms of how many moles are present in each liter of solution. It’s a practical and widely used way to express how much chemical substance is present per unit volume.

Molality uses kilograms of solvent rather than liters of solution, which makes it less sensitive to temperature-induced volume changes. Normality expresses equivalents per liter and depends on the chemical reactivity of the solute, not just its mole amount. Density is mass per volume and tells you how heavy the solution is, not how many moles of solute are present. For example, dissolving 2 moles in 1 liter of solution gives a molarity of 2 M.