Question

Sand and sawdust cannot be separated by handpicking

Answer 1

Explanation:

(a) Because in hand picking method substances should be large enough in size to be recognized and picked out by hand but sand and saw dust particles are very small in size so they can’t be picked by hand. It can be separated by filtration.

(b) Mixtures of iron and sulphur can be separated by moving a magnet over them. Iron gets attached to the magnet is separated.

(c) Water from a river, pond or lake contains very fine clay particles. To make them settle at a faster rate, a chemical substance called alum in powdered form is added to such mixtures. It dissolves in water and forms clusters with clay and dust particles making them heavier and increasing the rate of sedimentation.