c
\(BaSO_4\rightleftharpoons Ba^{2+} + SO_4^{2-}\)      \(k_{sp}=s^2 \)   \(\therefore s = \sqrt {{k_{sp}}} \)

 

\(Ca_3(PO_4)_2\rightleftharpoons 3Ca^{2+} + 2PO_4^{3-}\)      \(k_{sp}=(3S)^3\times  (2S)^2=108s^5\)    \(\therefore \,\,s\, = \,\,{\left( {\frac{{{K_{sp}}}}{{108}}} \right)^{1/5}}\)

\(Hg_2Cl_2\rightleftharpoons Hg_2^{2+}+2Cl^-\)     \(k_{sp} =  S \times (2s)^2 = 4s^3\)  \(\therefore \,\,\,s\,\, = \,\,{\left( {\frac{{{K_{sp}}}}{4}} \right)^{1/3}}\)

\(Ag_3PO_4  \rightleftharpoons   3Ag^++PO_4^{3-}\)     \(k_{sp} = (3s)^3 \times s = 27s^4\) \(\therefore \,\,s\,\, = \,\,{\left( {\frac{{{K_{sp}}}}{{27}}} \right)^{1/4}}\)

\(Cus \rightleftharpoons  Cu^{2+}+s^{2-} \,\,,k_{sp}=s^2\) \(\therefore \,\,s\,\, = \,\,\sqrt {ksp} \)