Question

Assertion (A): Molality of solution increases with temperature. Reason (R): Molality expression does not involve any volume term.

• A. Both A and R are correct, R is the correct explanation of A.
• B. Both A and R are correct, R is not the correct explanation of A.
• C. A is correct, R is not correct.
• D. A is not correct, R is correct.

Hint:

Molality depends on mass, while molarity depends on volume. Since volume changes with temperature but mass does not, molarity changes with temperature whereas molality remains constant.

Answer 1

The Correct Option is D

Step 1: Distinguish assertion from reason.
Molality = moles solute/kg solvent. Mass doesn't change with temperature, so molality stays constant → Assertion (A) is false. Reason correctly notes molality uses mass, not volume, so it's temperature-independent → Reason (R) true.

Step 2: Final Answer:
A not correct, R correct (option 4).