Which one of the following statement is incorrect

Options

A. Greater the lowering of vapour pressure, greater is the boiling point of the solution
B. Greater the lowering of vapour pressure, greater is the freezing point of the solution
C. At the freezing point, the solute and the solvent have same vapour pressure
D. the units of molal depression constant are `Km^(-1)`

Answer

To determine which statement is incorrect among the given options, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Analyzing Statement A**:
- Statement A claims: "Greater is the lowering in vapor pressure, greater is the boiling point of the solution."
- **Explanation**: The boiling point of a solution increases when the vapor pressure decreases. This is because a lower vapor pressure means that more heat is required to reach the boiling point. Therefore, this statement is correct.

2. **Analyzing Statement B**:
- Statement B claims: "Greater is the lowering of vapor pressure, greater is the freezing point of the solution."
- **Explanation**: This statement is incorrect. In fact, as the vapor pressure decreases, the freezing point of the solution also decreases. Therefore, greater lowering of vapor pressure results in a lower freezing point, making this statement incorrect.

3. **Analyzing Statement C**:
- Statement C claims: "At freezing point, the solute and solvent have the same vapor pressure."
- **Explanation**: This statement is correct. At the freezing point, the vapor pressures of the solute and solvent become equal, allowing the phase transition to occur. Thus, this statement is correct.

4. **Analyzing Statement D**:
- Statement D claims: "The units of molar depression constant (kf) are scaled with molar inverse."
- **Explanation**: The molar depression constant (kf) is indeed expressed in terms of molal units (m), which is moles of solute per kilogram of solvent. The relationship ΔTf = kf × m confirms that kf has units that are compatible with the units of molality (m). Therefore, this statement is correct.

### Conclusion:
- The incorrect statement is **Statement B**: "Greater is the lowering of vapor pressure, greater is the freezing point of the solution."