Question

Desalination of water is associated with

• A. Osmotic pressure
• B. Elevation in temperature
• C. Decrease in freezing point
• D. Relative decrease in partial pressure.

Answer 1

The correct option is A Osmotic pressure

Osmotic pressure is used for desalination by causing reverse osmosis. In reverse osmosis, pressure higher than osmotic pressure is applied which causes the movement of solvent (water) across the semi permeable membrane leaving the salt behind.

Elevation in temperature, Decrease in freezing point and Relative decrease in partial pressure are all colligative properties that depend on the concentration of solute (salt) in the solvent (water). These are not purification or separation methods.

So the correct answer is ' Osmotic pressure'.