Which of the following conditions is not correct for ideal solution:

Options

A. no change in volume on mixing
B. no change in enthalpy on mixing
C. it obey's Raoult's law
D. Ionisation of solute should occurs to a small extent

Answer

To determine which condition is not correct for ideal solutions, we need to understand the characteristics of ideal solutions. Here’s a step-by-step breakdown of the solution:

### Step 1: Define Ideal Solutions
Ideal solutions are those that obey Raoult's law at all temperatures and pressures. This means that the vapor pressure of the solution is directly proportional to the mole fraction of the solvent.

### Step 2: Identify Key Characteristics
1. **No Change in Volume on Mixing**: For an ideal solution, the volume before and after mixing remains the same. This means that the change in volume (ΔV) during mixing is zero.

2. **No Change in Enthalpy on Mixing**: Ideal solutions also exhibit no change in enthalpy during mixing (ΔH = 0). This indicates that the interactions between the solute and solvent are similar to those between the molecules of the pure components.

3. **Obey Raoult's Law**: Ideal solutions must obey Raoult's law, which states that the partial vapor pressure of each component in the solution is equal to the vapor pressure of the pure component multiplied by its mole fraction in the solution.

### Step 3: Analyze the Options
Now, we will evaluate the given options to identify which one is not correct for ideal solutions:

- **Option A**: No change in volume on mixing - This is correct for ideal solutions.
- **Option B**: No change in enthalpy of mixing - This is also correct for ideal solutions.
- **Option C**: It obeys Raoult's law - This is correct as well.
- **Option D**: Ionization of solute should occur to a smaller extent - This is the option we need to evaluate further.

### Step 4: Evaluate Option D
For ideal solutions, the ionization of the solute should occur to a larger extent, not a smaller extent. This means that when a solute ionizes, it should do so significantly to maintain the ideal behavior of the solution. Therefore, stating that ionization should occur to a smaller extent is incorrect.

### Conclusion
The condition that is not correct for ideal solutions is:
**Ionization of solute should occur to a smaller extent.**

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