Question

A saturated Ni(OH)_2_ can be prepared by dissolving 0.239 mg of Ni(OH)_2_ in water to make 500.0 mL of solution. What is the Ksp for Ni(OH)_2_?

Answer 1

M Ni(OH)2 = moles/L.
You have grams, convert to moles and you have L. That is the solubility of Ni(OH)2 which I will call x for simplicity.
.........Ni(OH)2 ==> Ni^2+ + 2OH^-
...........x.........x..........2x
Substitute into Ksp expression and solve for Ksp.