Read the Passage and answer the following question:

There are many properties of ideal solutions which depends only on the concentration of the solute particles and are independent of the nature of the solute. Such properties are called colligative properties. For example, when a non-volatile solute is added to a solvent, its vapour pressure gets lowered. Raoult established that relative lowering in vapour pressure depends only on the concentration of the solute and it is independent of its identity. Similarly, elevation in boiling point, depression in freezing point and osmotic pressure on addition of a non volatile solute to a solvent depend only on the concentration of solute but are independent of its nature. These properties can also be used to determine the molar mass of the solute. The relative lowering in vapour pressure changes when the solute is electrolyte and undergoes association or dissociation in the solution. The molar mass obtained in these electrolytic solutions are abnormal molar masses. 

Which of the following colligative properties can provide molar mass of proteins (or polymers or colloids) with greatest precision?

Osmotic Pressure

The correct answer is option 2. Osmotic Pressure.

To determine the molar mass of proteins, polymers, or colloids with the greatest precision, the most suitable colligative property is Osmotic Pressure

1. Depression in Freezing Point:

This method involves measuring the lowering of the freezing point of a solvent when a solute is dissolved in it. While it can be used for determining molar masses, it is less precise for large molecules like proteins or polymers because the freezing point depression is often very small, making it difficult to measure accurately for dilute solutions.

2. Osmotic Pressure:

Osmotic pressure is the pressure required to stop the flow of solvent into the solution through a semipermeable membrane. It is directly proportional to the molarity of the solute, making it highly sensitive to the presence of solute particles, even at very low concentrations. This high sensitivity and the relatively large magnitude of osmotic pressure changes make it particularly suitable for determining the molar masses of large molecules such as proteins, polymers, and colloids with high precision.

3. Relative Lowering of Vapour Pressure:

This method involves measuring the reduction in the vapor pressure of a solvent when a non-volatile solute is added. While it can provide information on molar mass, it is less precise for high-molecular-weight substances because the changes in vapor pressure can be quite small and difficult to measure accurately.

4. Elevation in Boiling Point:

This method involves measuring the increase in the boiling point of a solvent when a solute is dissolved in it. Similar to the freezing point depression, the boiling point elevation is typically very small for large molecules, making it less precise for determining the molar mass of proteins or polymers.

Among these colligative properties, osmotic pressure provides the greatest precision for determining the molar mass of proteins, polymers, and colloids due to its high sensitivity to solute concentration and the relatively large changes in pressure that can be measured accurately, even for large molecules.