Define the term ' osmotic pressure' . Descibe how the molecular mass of a substance can be determined on the basis of pressrure measurement.

Explanation

**Step-by-Step Solution:**

**Step 1: Define Osmotic Pressure**
Osmotic pressure is defined as the pressure required to prevent the flow of solvent molecules through a semipermeable membrane from a dilute solution to a concentrated solution. It is a colligative property that depends on the concentration of solute particles in the solution.

**Step 2: Explanation of the System**
Consider a system where a semipermeable membrane separates two solutions: one with a solute (concentrated solution) and the other with pure solvent (dilute solution). The solvent molecules tend to move from the area of lower solute concentration to the area of higher solute concentration. The osmotic pressure is the pressure that must be applied to the concentrated side to stop this flow.

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