Question

Assertion :On mixing $500mL$ of ${10}^{-6}M$ ${Ca}^{2+}$ ion and $500mL$ of ${10}^{-6}M$ $F^{-}$ ion, the precipitate of $Ca{F}_2$ will be obtained.
$K_{sp}\left(Ca{F}_2\right)={10}^{-18}$ Reason: If $K_{sp}$ is greater than ionic product, precipitate will be obtained.

• 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. Both Assertion and Reason are incorrect

Answer 1

The correct option is D Both Assertion and Reason are incorrect

$K_{sp}={10}^{-18}$

$\left[C{a}^{2+}\right]=\frac{500\times {10}^{-6}}{1000}=0.5\times {10}^{-6}$

$\left[F^{-}\right]=\frac{500\times {10}^{-6}}{1000}=0.5\times {10}^{-6}$

$K_{ip}=\left[C{a}^{2+}\right][F^{-}{]}^2=(0.5\times {10}^{-6}\left)\right(0.5\times {10}^{-6}{)}^2=0.125\times {10}^{-18}<K_{sp}$

So precipitate will not form.