The two isomers X and Y with the formula `Cr(H_(2)O)_(5)ClBr` were taken for experiment on depression in freezing point. It was found that one mole of X gave depression corresponding to 2 moles of particles and one mole of Y gave depression to 3 moles of particles. The structural formulae of X and Y raspectively are

Options

A. `[Cr(H_(2)O)_(5)Cl]Br_(2),[Cr(H_(2)O)_(4)Br_(2)]Cl.H_(2)O`
B. `[Cr(H_(2)O)_(5)Cl]Br_(2),[Cr(H_(2)O)_(3)ClBr_(2)].2H_(2)O`
C. `[Cr(H_(2)O)_(5)Br]Br Cl, [Cr(H_(2)O)_(4)ClBr]Br.H_(2)O`
D. `[Cr(H_(2)O)_(4)Br_(2)]Cl.H_(2)O,[Cr(H_(2)O)_(5)Cl]Br_(2)`

Answer

D

Explanation

Depression in freezing point is a colligative property that depends upon the number of moles of ions which a complex may give in solution.
X gave depression corresponding to 2 moles of particles. It means 2 mol of ions of a complex is present in solution, which is only possible when complex is in the form `[Cr(H_(2)O)_(4)Br_(2)]Cl`. `H_(2)O` or `[Cr(H_(2)O)_(5)Cl]Br_(2) or [Cr(H_(2)O)_(5)Cl]^(+)+2Br^(-)`.