Statement-I: Relative lowering of vapour pressure is equal to mole fraction of the solvent.
Because
Statement-II: Relative lowering of vapour pressure is a colligative property.

Answer

To analyze the statements provided in the question, we will break down the concepts involved and evaluate the correctness of each statement step by step.

### Step 1: Understanding Vapor Pressure
- **Vapor Pressure**: It is the pressure exerted by a vapor in equilibrium with its liquid or solid phase. For a pure solvent, this pressure is denoted as \( P^0 \).

**Hint**: Remember that vapor pressure is a measure of the tendency of a substance to evaporate.

### Step 2: Effect of a Non-Volatile Solute
- When a non-volatile solute is dissolved in a solvent, the vapor pressure of the solvent decreases. This is because the solute particles occupy space at the surface of the liquid, reducing the number of solvent molecules that can escape into the vapor phase.

**Hint**: Consider how adding solute affects the number of solvent molecules available to evaporate.

### Step 3: Relative Lowering of Vapor Pressure
- The relative lowering of vapor pressure can be expressed mathematically:
\[ \text{Relative lowering of vapor pressure} = \frac{P^0 - P}{P^0} \]
where \( P \) is the vapor pressure of the solution and \( P^0 \) is the vapor pressure of the pure solvent.

**Hint**: Focus on how the presence of solute changes the vapor pressure compared to the pure solvent.

### Step 4: Mole Fraction of Solvent and Solute
- The relationship between the vapor pressure and the mole fraction of the solute is given by Raoult's Law:
\[ P = x \cdot P^0 \]
where \( x \) is the mole fraction of the solvent. The mole fraction of the solute is \( 1 - x \).

**Hint**: Recall that mole fractions are fractions of the total number of moles, and they must add up to 1.

### Step 5: Evaluating Statement I
- **Statement I**: "Relative lowering of vapor pressure is equal to mole fraction of the solvent."
- This statement is incorrect because the relative lowering of vapor pressure is actually related to the mole fraction of the solute, not the solvent.

**Hint**: Identify which component (solute or solvent) the relative lowering of vapor pressure is associated with.

### Step 6: Evaluating Statement II
- **Statement II**: "Relative lowering of vapor pressure is a colligative property."
- This statement is correct. Colligative properties depend on the number of solute particles in a solution, not on their identity.

**Hint**: Recall the definition of colligative properties and how they relate to the number of solute particles.

### Conclusion
- **Final Evaluation**:
- Statement I is **incorrect**.
- Statement II is **correct**.

Thus, the answer is that Statement I is false, and Statement II is true.