[Mg2+]=x [OH-]=2x

So 4x 3 = ksp solution.

2.[OH-]=0.0 1

Because the hydroxyl contribution of magnesium hydroxide can be ignored, it can be ignored.

So the solubility is ksp/0.012.

3.[Mg2+]= 0.0 1 mol/L.

Because the magnesium ion contribution of magnesium hydroxide can be ignored, it can be ignored.

So the solubility is (ksp/0.0 1) 0.5/2 (two hydroxyl groups).