Which of the following statements with reference to a solution are correct?
(A) the molarity of the solution changes with the change in the temperature.
(B) the volume of the solution changes with the change in the temperature.
(C) the molality of the solution changes with the change in the temperature.
(D) the normality of the solution changes with the change in the temperature.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → (A), (B) and (D) only
A concentration term changes with temperature if it contains the volume of the solution, because liquids expand on heating. Terms based only on masses (mass %, mole fraction, molality) do not change, since mass does not depend on temperature.
(A) the molarity of the solution changes with the change in the temperature. — Correct. Molarity is moles of solute per litre of solution; the volume, and so the molarity, changes with temperature.
(B) the volume of the solution changes with the change in the temperature. — Correct. A solution expands on heating and contracts on cooling.
(C) the molality of the solution changes with the change in the temperature. — Incorrect. Molality is moles of solute per kilogram of solvent; both quantities are masses, so it is independent of temperature.
(D) the normality of the solution changes with the change in the temperature. — Correct. Normality is gram equivalents per litre of solution, so, like molarity, it changes with the volume.
NCERT (2026-27 edition):
Expressing Concentration of Solutions – …
