Question

multiple choice question
what is osmotic pressure?

the amount of water pressure exerted by a solution
the rate at which water is moving due to random molecular motion
the amount of pressure needed to oppose osmosis
the pressure that solute particles exert to cause osmosis

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Explanation:

To determine the correct definition of osmotic pressure, we analyze each option:

• The first option ("The amount of water pressure exerted by a solution") is incorrect as osmotic pressure is not just water pressure from the solution.
• The second option ("The rate at which water is moving due to random molecular motion") describes diffusion or Brownian motion, not osmotic pressure.
• The third option ("The amount of pressure needed to oppose osmosis") matches the definition of osmotic pressure: it's the pressure required to stop the net flow of solvent (usually water) across a semipermeable membrane due to osmosis.
• The fourth option ("The pressure that solute particles exert to cause osmosis") is incorrect because solute particles don't exert pressure to cause osmosis; osmosis is driven by the concentration gradient of solvent.

Answer:

C. The amount of pressure needed to oppose osmosis