Given below are two statements, one labelled as Assertion (A) and the other labelled as Reason (R). Choose the correct answer from the options given below. Assertion (A): The molality of KCl solution at 25°C is 5 m. (Given molar mass of KCl is 74.5 g/mol). When the solution is cooled to -10°C, the molality of the solution remains unchanged. Reason (R): The molality of the solution does not change with temperature as

Step-by-step solution

Molality = moles of solute mass of solvent in kg Since mass is independent of temperature (unlike volume), molality does not change with temperature. So Reason (R) is true. A 5 m KCl solution has a highly depressed freezing point ( -18.6°C ), so it remains liquid at -10°C and its molality stays unchanged. So Assertion (A) is also true. R correctly explains A, hence both A and R are true and R is the correct explanation of A.