Which of the following is incorrect

Options

A. Relative lowering of vapour pressure is independent
B. The vapour pressure is a colligative property
C. Vapour pressure of a solution is lower than the vapour pressure of the solvent
D. The relative lowering of vapour pressure is directly oroportional to the original pressure

Explanation

To determine which statement is incorrect regarding vapor pressure and colligative properties, we will analyze each option step by step.

### Step-by-Step Solution:

1. **Understanding Relative Lowering of Vapor Pressure (RLVP)**:
- The relative lowering of vapor pressure is defined as:
\[ \text{RLVP} = \frac{P_0 - P_s}{P_0} \]
where \( P_0 \) is the vapor pressure of the pure solvent and \( P_s \) is the vapor pressure of the solution.

2. **Analyzing the First Statement**:
- The first statement claims that "relative lowering of vapor pressure is independent."
- This is **correct** because RLVP is proportional to the mole fraction of the solute, not dependent on the number of solute particles.

3. **Analyzing the Second Statement**:
- The second statement asserts that "vapor pressure is a colligative property."
- This is also **correct** as colligative properties depend on the number of solute particles in a solution, not their identity.

4. **Analyzing the Third Statement**:
- The third statement states that "the vapor pressure of a solution is lower than the vapor pressure of the solvent."
- This is **correct** because adding a non-volatile solute to a solvent lowers its vapor pressure.

5. **Analyzing the Fourth Statement**:
- The fourth statement claims that "relative lowering of vapor pressure is directly proportional to the mole fraction of non-volatile solute."
- This statement is **incorrect**. The relative lowering of vapor pressure is inversely proportional to the mole fraction of the solvent, not directly proportional to the mole fraction of the solute.

### Conclusion:
The incorrect statement is the fourth one: "relative lowering of vapor pressure is directly proportional to mole fraction of non-volatile solute."