Which of the following best describes the process of reverse osmosis?

Reverse osmosis is a water purification process that involves applying pressure to overcome the natural osmotic pressure, allowing water to flow through a semipermeable membrane. This membrane only allows certain molecules or ions to pass through while blocking larger particles and contaminants.

Applying pressure is crucial in reverse osmosis as it forces water molecules from the more concentrated solution (containing impurities and solutes) to move to the less concentrated solution on the opposite side of the membrane. This process effectively removes impurities, including salts, bacteria, and other contaminants, resulting in purified water.

Understanding this process highlights the importance of pressure in enabling the movement of water in the reverse direction, which is contrary to the natural osmotic flow where water tends to move from an area of lower solute concentration to an area of higher solute concentration.