Question

Give reason:
a. Sugar and water can be separated by crystallisation technique.
b. Salt from seawater can be separated by evaporation technique.

Answer 1

a. Pure substance is obtained by the crystallisation process. The sugar solution gets heated and the water gets evaporated. When little water is left to evaporate the solution is cooled down. The sugar starts to dissolve and starts to separate out in the form of crystals.
b. Evaporation technique is used to separate homogeneous solid - liquid mixture like salt in seawater. The seawater is collected in the shallow beds then it is allowed to evporate in the sun thus, leaving the salt behind once the water is evaporated.