Hi Candidate,

The solubility of the salt is almost always decreased by the presence of a common ion and the Sparingly soluble materials are those, which have lowered solubility.

Usually materials are treated as sparingly soluble if 1g of material requires 30 to 100ml of solute to dissolve. The ionic diameter is given by the Ionic Activity coefficient × gamma, and taking the mean of the sum.

Due to the device limitations, I can't solve it here, but you can try it out with pen and paper.

Hope that this answer helps you.