Which statement best defines osmosis?

Which statement best defines osmosis?

• A. It is the movement of solvent across a semipermeable membrane from areas of lower solute concentration to areas of higher solute concentration
• B. It is the diffusion of solute molecules through a semipermeable membrane
• C. It is the movement of solvent across a semipermeable membrane from areas of lower solute concentration to areas of higher solute concentration
• D. It is the mixing of two immiscible liquids

Answer: (C)

Osmosis is the movement of solvent, such as water, across a semipermeable membrane from areas of lower solute concentration to areas of higher solute concentration. The membrane allows the solvent to pass but restricts the solute, so water flows to dilute the side with more solute and move toward equalizing concentrations. This distinction matters because osmosis is about solvent movement, not solute; diffusion of solute through the membrane would be general diffusion, not osmosis. Mixing two immiscible liquids isn’t osmosis either, since it involves separate liquid layers rather than solvent crossing a membrane.

Osmosis is the movement of solvent, such as water, across a semipermeable membrane from areas of lower solute concentration to areas of higher solute concentration. The membrane allows the solvent to pass but restricts the solute, so water flows to dilute the side with more solute and move toward equalizing concentrations. This distinction matters because osmosis is about solvent movement, not solute; diffusion of solute through the membrane would be general diffusion, not osmosis. Mixing two immiscible liquids isn’t osmosis either, since it involves separate liquid layers rather than solvent crossing a membrane.