Question

Assertion :Heat of solution is positive when ${Na}_2{SO}_4\cdot 10H_{2}O$ is dissolved in water but it is negative when anhydrous $Cu{SO}_4$ is dissolved in water. Reason: Molar masses of ${Na}_2{SO}_4\cdot 10H_{2}O$ and $Cu{SO}_4$ are different.

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

Answer 1

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

The heat of solution is positive when anhydrous $CuS{O}_4$ is dissolved in water because exra amount of heat is released when water added as water of crystalization in $CuS{O}_4$ but in case of $N{a}_{2}S{O}_4.10H_{2}O$ is already having water of crystallization attached to it.