Question

A teacher gave an impure sample of alum containing fine sand as impurity to a student. He asked him to recover pure alum from this sample. The correct procedure to be followed would be to :
(1) dissolve the impure sample of alum in water, filter and evaporate the filtrate
(2) dissolve the impure sample of alum in alcohol and filter
(3) move a magnet over the impure sample of alum
(4) dissolve the impure sample of alum in carbon disulphide, filter and evaporate the filtrate

Answer 1

To prepare the pure alum, first, dissolve the impure alum in water than filter it. All the insoluble impurities remain in the filter paper. Then evaporate the water and pure alum will be obtained.

Hence, the correct answer is option 1.