GIVEN as:\({\RM{Z}}{{\rm{r}}_3}{\left( {{\rm{P}}{{\rm{O}}_4}} \right)_4}⇌3{\rm{Z}}{{\rm{r}}^{4 + }} + 4{\rm{PO}}_4^{3 - }\) 3S 4SThe solubility of Zr3(PO4)4\({{\rm{K}}_{{\rm{sp}}}} = {\left[ {3{\rm{Z}}{{\rm{r}}^{4 + }}} \right]^3}{\left[ {4{\rm{PO}}_4^{3 - }} \right]^4}\)Calculation:⇒ Ksp = [3S]3 [4S]4⇒ Ksp = 27S3 × 256S4⇒ Ksp = 6912S7\(\Rightarrow {{\rm{S}}^7} = \frac{{{{\rm{K}}_{{\rm{sp}}}}}}{{6912}}\)\(\therefore {\rm{S}} = {\left( {\frac{{{{\rm{K}}_{{\rm{sp}}}}}}{{6912}}} \right)^{1/7}}\)