A mixture of two colourless substances was dissolved in water. When gaseous Cl₂ was passed through the solution, containing small quantity of CCl₄ a violet colour developed in organic layer. Addition of BaCl₂ to the original solution give a white precipitate. The mixture contains :

${\mathrm{MgI}}_2$ and ${\mathrm{MgSO}}_4$are both present in the combination.
Magnesium sulphate and barium chloride react to produce white ppt of barium hydroxide.
White ppt of magnesium hydroxide is created when sodium hydroxide and magnesium iodide combine. Magnesium sulphate and $\mathrm{NaOH}$ react to produce ppt with the same colour.
Brown ppt is created when magnesium salts and chlorine gas combine.

${\mathrm{Cl}}_2+2\mathrm{KI}⟶2\mathrm{KCl}+{\mathrm{I}}_2\text{ (violet); }$

${\mathrm{BaCl}}_2+{\mathrm{SO}}_4^{2-}⟶{\mathrm{BaSO}}_4\downarrow \text{ (white ppt.) }$