The relationship `piv=nRT` is not obeyed by

Options

A. Concentrated solution
B. Dilute solution
C. Extremely dilute solution
D. All the above

Answer

To solve the question regarding the relationship \( \Pi V = nRT \) and identify the condition under which it is not obeyed, follow these steps:

### Step-by-Step Solution:

1. **Understand the Equation**: The equation \( \Pi V = nRT \) is known as the van 't Hoff equation for osmotic pressure (\( \Pi \)). Here, \( \Pi \) is the osmotic pressure, \( V \) is the volume of the solution, \( n \) is the number of moles of solute, \( R \) is the universal gas constant, and \( T \) is the temperature in Kelvin.

2. **Identify the Conditions**: The question asks under which conditions this relationship does not hold. The options given are concentrated solution, dilute solution, and extremely dilute solution.

3. **Analyze Each Condition**:
- **Concentrated Solution**: In concentrated solutions, there are enough solute particles to exert osmotic pressure, so the equation holds true.
- **Dilute Solution**: In dilute solutions, while the concentration is low, there are still enough solute particles to create a measurable osmotic pressure, so the equation also holds true.
- **Extremely Dilute Solution**: In extremely dilute solutions, the concentration of solute particles becomes so low that the osmotic pressure approaches zero. In this case, the assumptions of the equation break down, and it does not accurately describe the behavior of the solution.

4. **Conclusion**: Based on the analysis, the relationship \( \Pi V = nRT \) is not obeyed by extremely dilute solutions. Therefore, the correct answer is **extremely dilute solution**.

### Final Answer:
The relationship \( \Pi V = nRT \) is not obeyed by **extremely dilute solutions**.

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