Molarity is defined as

• A. Moles per liter of solvent
• B. Moles per liter of solution
• C. Grams per liter
• D. Moles per kilogram of solvent

Answer: (B)

Molarity is the amount of solute, in moles, present in one liter of the entire solution. This means the volume used is the total solution, including dissolved substances, which is why molarity can change with temperature as liquids expand or contract. In contrast, grams per liter measures mass concentration, and molality uses kilograms of solvent (not liters of solution), so it behaves differently with temperature. Therefore, the correct definition is moles per liter of solution.