The osmotic pressure of a solution can be increased by

Options

A. increasing the volume
B. increasing the number of solute molecules
C. decreasing the temperature
D. removing semipermeable membrane

Explanation

To solve the question regarding how to increase the osmotic pressure of a solution, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Osmotic Pressure Formula**:
The osmotic pressure (\( \pi \)) of a solution is given by the formula:
\[ \pi = C \cdot R \cdot T \]
where \( C \) is the concentration of the solution, \( R \) is the gas constant, and \( T \) is the temperature in Kelvin.

2. **Analyze Each Option**:
- **Option A: Increasing the Volume**:
Increasing the volume of the solution will decrease the concentration (\( C \)), as concentration is defined as the number of moles of solute divided by the volume of the solution. Therefore, increasing the volume will decrease osmotic pressure. This option is incorrect.

- **Option B: Increasing the Number of Solute Molecules**:
If we increase the number of solute molecules while keeping the volume constant, the concentration (\( C \)) will increase. Since osmotic pressure is directly proportional to concentration, increasing the number of solute molecules will increase the osmotic pressure. This option is correct.

- **Option C: Decreasing the Temperature**:
Since osmotic pressure is directly proportional to temperature (\( T \)), decreasing the temperature will decrease the osmotic pressure. This option is incorrect.

- **Option D: Removing the Semi-Permeable Membrane**:
The semi-permeable membrane is essential for osmosis to occur. Removing it would mean that osmosis cannot take place, and thus osmotic pressure would not be relevant. This option is incorrect.

3. **Conclusion**:
Based on the analysis, the correct answer is:
**B: Increasing the number of solute molecules** will increase the osmotic pressure of the solution.