Question

Assertion :Solubility of $BaS{O}_4$ in 0.1 M $N{a}_{2}S{O}_4$ is ${10}^{-9}$ M hence its $K_{sp}$ is ${10}^{-18}$. Reason: For $BaS{O}_4,K_{sp}=(s{)}^2$.

• 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 incorrect but Reason is correct
• D. Both Assertion and Reason are incorrect

Answer 1

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

If S M is the solubility of $BaS{O}_4$ then,

$K_{sp}=\left[B{a}^{2+}\right]\left[S{O}_4^{2-}\right]=s\times s=s^2$

Hence, the reason is correct.

In presence of 0.1 M $N{a}_{2}S{O}_4$, $s={10}^{-9}M=\left[B{a}^{2+}\right]$
Also $\left[S{O}_4^{2-}\right]=0.1M$.

Hence, the value of the solubility product is $K_{sp}=\left[B{a}^{2+}\right]\left[S{O}_4^{2-}\right]={10}^{-9}\times 0.1={10}^{-10}$

Hence, the assertion is incorrect.