Correct Answer - B
When heated, hydrated magnesium chloride is hydrolyzed by its water of crystallization with the evolution of hydrogen chloride and the formation chloride a the formation of the oxide:
`MgCl_(2).6H_(2)Ooverset(Delta)toMgO+2HCl+5H_(2)O`
or `MgCl_(2)(s)+H_(2)O(l)toMgO(l)+2HCl`
It is , therefore, not possible to obtain the anhydrous chloride b evaporation of an aquous solution of the chloride. How ever, it can be obtained if the evaporation is carried out in a stream of hydrogen chloride which has the effect of reversing the above reaction. Hydrated `CaCl_(2)` also suffers hydrolysis on heaing but to markedly less extent.
