From the colligative properties of solution which one is the best method for the determination of mol.wt of proteins & polymers:

Options

A. osmotic pressure
B. lowering in vapour pressure
C. loweing in freezing point
D. elevation in B.Pt

Answer

To determine the best method for the determination of molecular weight of proteins and polymers from the colligative properties of solutions, we can analyze each option provided:

### Step 1: Understand Colligative Properties
Colligative properties depend on the number of solute particles in a solution and not on the nature of the solute. The main colligative properties are:
- Lowering of vapor pressure
- Freezing point depression
- Boiling point elevation
- Osmotic pressure

### Step 2: Analyze Each Option
1. **Lowering in Vapor Pressure**:
- This property is not very effective for large molecules like proteins and polymers because the change in vapor pressure is relatively small for high molecular weight solutes.

2. **Lowering in Freezing Point**:
- Similar to vapor pressure lowering, the depression in freezing point is also minimal for macromolecules, making it less suitable for determining their molecular weight.

3. **Elevation in Boiling Point**:
- Like the previous two properties, the elevation in boiling point is not significant for large molecules, thus it is not the best method for molecular weight determination.

4. **Osmotic Pressure**:
- Osmotic pressure is a colligative property that can be effectively used for large molecules. It is measured at room temperature, and since proteins and polymers do not change their properties significantly at this temperature, osmotic pressure provides a more accurate measure for determining their molecular weight.

### Step 3: Conclusion
Based on the analysis, the best method for the determination of molecular weight of proteins and polymers is **Option A: Osmotic Pressure**. This method is preferred because it is not affected by temperature changes and provides a more significant measurement for large macromolecules.

### Final Answer:
**The best method for the determination of molecular weight of proteins and polymers is Option A: Osmotic Pressure.**

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