Two sparingly soluble salts AB and XYZ have the same soubility product. Which salt will be more soluble?

Explanation

Let the solubility of `AB=S_(1)mol L^(-1)`
The solubility of `xy_(2)=S_(2)mol L^(-1)`
`AB hArrA^(+)+B^(-)`
`{:(1,0,0),(1-S_(1),S_(1),S_(1)):}`
`K_(sp)=[A^(+)][B^(-)]`
`K_(sp)=S_(1)^(2)`
`S_(1)=(K_(sp))^(1//2)`
`xy_(2)hArrx^(+2)+2y^(-1)`
`{:(1,0,0),(1-S_(2),S_(2),2S_(2)):}`
`k_(sp)=[X^(+2)][2y^(-)]^(2)`
`=4S_(2)^(3)`
`S_(2)=[(K_(sp))/(4)]^(1//4)`
Obviously `S_(2)gtS_(1)(as k_(sp)` have values with negative power of 10). hence salt `xy_(2)` is more soluble.