Exam Question

### (a) Principle of Reverse Osmosis
The principle of Reverse Osmosis (RO) is best understood by first defining normal Osmosis.
**1. Osmosis:**
Osmosis is a naturally occurring physical phenomenon. When two solutions of different concentrations are separated by a semi-permeable membrane, the solvent (in this case, pure water) will spontaneously move from the solution of lower solute concentration (dilute) to the solution of higher solute concentration (concentrated). This movement continues until equilibrium is reached, generating a pressure difference across the membrane known as **Osmotic Pressure**.