Question

Assertion: Molarity of a solution in liquid state changes with temperature.

Reason: The volume of a solution changes with change in temperature

• A. Assertion and reason both are incorrect statements.
• B. Assertion is wrong statement but the reason is correct statement.
• C. Assertion is correct statement but the reason is wrong statement
• D. Assertion and reason both are correct statements and reason is the correct explanation for assertion.
• E. Assertion and reason both are correct statements but the reason is not the correct explanation for assertion.

Answer 1

The correct option is D

Assertion and reason both are correct statements and reason is the correct explanation for assertion.

Analysing the assertion :

Molarity $\left(M\right)$ of a solution is defined as the number of moles of the solute dissolved per litre of the solution.

$\text{Molarity(M)}=\frac{\left(\text{moles of solute}\right)}{\left(\text{volume of solution (in L)}\right)}$

Molarity depends on volume, which changes with temperature. Therefore, molarity changes with temperature. So, the assertion is a correct statement.

Analysing the reason :

When temperature increases, the volume of the solution also increases, assuming the solution is at constant pressure condition and molarity decreases. So, the reason is also a correct statement.

So, both the assertion and the reason are correct statements, and the reason is the correct explanation for the assertion.

Hence, option (A) is the correct answer.