A sample of a hydrate of barium chloride weighing 61 g was heated until all the water of hydration is removed. The dried sample weighed $52\; g$. The formula of the hydrated salt is : (atomic mass, $Ba=137 \;amu,\; Cl = 35.5 \;amu$)

Question

( A ) $BaCl_2.H_2O$
( B ) $BaCl_2. 2H_2O$
( C ) $BaCl_2. 4H_2O$
( D ) $BaCl_2.3H_2O$