A solution with osmotic pressure `pi_(1)` is separated from another solution of osmotic pressure `pi_(2)` by SPM solvent flows from `pi_(1) to pi_(2)`, then

Options

A. `pi_1 gt pi_2`
B. `pi_1 lt pi_2`
C. Solutions are isotonic
D. Solutions are ideal

Answer

To solve the problem, we need to analyze the flow of solvent between the two solutions separated by a semi-permeable membrane (SPM) based on their osmotic pressures.

### Step-by-Step Solution:

1. **Understanding Osmotic Pressure**:
- Osmotic pressure (\( \pi \)) is the pressure required to stop the flow of solvent into a solution through a semi-permeable membrane. The greater the osmotic pressure, the stronger the tendency of the solvent to flow into that solution.

2. **Direction of Solvent Flow**:
- The problem states that the solvent flows from the solution with osmotic pressure \( \pi_1 \) to the solution with osmotic pressure \( \pi_2 \). This indicates that the solvent is moving towards the solution with higher osmotic pressure.

3. **Analyzing the Implication**:
- According to the principles of osmosis, solvent will naturally flow from an area of lower osmotic pressure to an area of higher osmotic pressure. Therefore, if the solvent is moving from \( \pi_1 \) to \( \pi_2 \), it implies that \( \pi_2 \) must be greater than \( \pi_1 \).

4. **Conclusion**:
- Since the solvent flows from \( \pi_1 \) to \( \pi_2 \), we conclude that:
\[ \pi_2 > \pi_1 \]
- Thus, the answer to the question is that \( \pi_1 \) is less than \( \pi_2 \).

### Final Answer:
- \( \pi_1 < \pi_2 \)

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