Question

Assertion :Molarity of an aqueous solution at $0^o$C is less than the molarity of the same solution at $4^o$C Reason: Molarity increases with an increase of temperature

• A. Both Assertion and Reason are correct and the Reason is the correct explanation of the Assertion
• B. Both Assertion and Reason are correct but the Reason is not the correct explanation of the Assertion
• C. The Assertion is correct but the Reason is incorrect
• D. The Assertion is incorrect but the Reason is correct

Answer 1

The correct option is C The Assertion is correct but the Reason is incorrect

The solution is aqueous. Mostly it contains water. Given temperatures are $0^{o}C$ to $4^{o}C$. Water shrinks when temperature increases from $0^{o}C$ to $4^{o}C$ due to the anomalous expansion of water.

$Molarity\propto \frac{1}{Volume}$

Generally with an increase in temperature, the volume of the substance increases, thus molarity decreases.

But in the case of an aqueous solution, with an increase in temperature from $0^{o}C$ to 4^oC$, the volume of water decreases, thus, the molarity increases.

Thus, Assertion is correct but the Reason is incorrect.