Solutions

Pure water can be obtained from sea water by

1. centrifugation
2. plasmolysis
3. reverse osmosis
4. sedimentation

Answer

(3) reverse osmosis

Solution

As per NCERT, if a pressure larger than the osmotic pressure is applied on the solution side, pure solvent flows out of the solution through the semipermeable membrane. This is called reverse osmosis.

It is used in desalination of sea water: when pressure greater than its osmotic pressure is applied to sea water, pure water is squeezed out through a membrane (e.g. cellulose acetate).

Answer: (3)