Answer
The answer for 4.18 is B.
Work Step by Step
You have to look at the ions to know the solubility .$ K^{+}$ ion is soluble in all aqueous solutions. $ Cl^{-}$ ion is also soluble in the given solution. But $OH^{-}$ ion is insoluble with $Mg^{2+}$ ion . So it forms a precipitate $Mg(OH)_{2}$ which settles at the bottom as shown in figure B.
