Write, in brief, (i) one physical and (ii) one chemical method that can be used for ‘water purification’.
(i) Physical method for ‘water purification’:
Filteration: Water can be purified by passing it through layers of sand, gravel and charcoal, one by one. This is a physical method of removing impurities. This has been, and can still be, the method that may be used in the absence of alternative and more advanced methods.
(ii) Chemical method for ‘water purification’:
Chlorination: This is a chemical method for purifying water. It is done by adding chlorine tablets (or bleaching powder) to water. This is a method that needs to be used with care. We should not use more chlorine tablets than specified.