Answer: B
The expression for the solubility product of \(CaF_2\) is \(K_{sp}=[Ca^{2+}][F^-]^2=1.7\times 10^{-10}\).
When equal volumes of \(10^{-4}M Ca^{2+}\)and\(10^{-4}M F^{-}\) are mixed.
\([Ca^{2+}][F^-]^2=(10^{-4})(10^{-4})^2=10^{-12}<1.7\times 10^{-10}\)
Thus the ionic product is less than the solubility product. Hence precipitation will not occur.
When equal volumes of \(10^{-2}M Ca^{2+}\)and\(10^{-3}M F^{-}\) are mixed.
\([Ca^{2+}][F^-]^2=(10^{-2})(10^{-3})^2=10^{-8}>1.7\times 10^{-10}\)
Thus the ionic product is more than the solubility product. Hence precipitation will occur.
Option B is correct.