Total vapour pressure of mixture of 1 mol volatile component `A(P^(@)A="100 mm Hg")` and 3 mol of volatile component
`B(P^(@)B="60 mm Hg")` is 75 mm. For such case -

Options

A. There is positive deviation from Raoult's law
B. Boiling point has been lowered
C. Force of attraction between A and B is smaller than that between A and A or between B and B.
D. All the above statements are correct

Answer

To solve the problem, we will use Raoult's law, which relates the vapor pressure of a solution to the vapor pressures of its components and their mole fractions.

### Step-by-Step Solution:

1. **Identify the Given Data:**
- Moles of component A (nA) = 1 mol
- Moles of component B (nB) = 3 mol
- Vapor pressure of pure A (P°A) = 100 mm Hg
- Vapor pressure of pure B (P°B) = 60 mm Hg
- Total vapor pressure of the mixture (P) = 75 mm Hg

2. **Calculate the Total Moles in the Mixture:**
\[ n_{total} = n_A + n_B = 1 + 3 = 4 \text{ mol} \]

3. **Calculate the Mole Fractions:**
- Mole fraction of A (X_A):
\[ X_A = \frac{n_A}{n_{total}} = \frac{1}{4} = 0.25 \]
- Mole fraction of B (X_B):
\[ X_B = \frac{n_B}{n_{total}} = \frac{3}{4} = 0.75 \]

4. **Apply Raoult's Law to Calculate Theoretical Vapor Pressure (P_theoretical):**
\[ P_{theoretical} = (X_A \cdot P°_A) + (X_B \cdot P°_B) \]
Substituting the values:
\[ P_{theoretical} = (0.25 \cdot 100 \text{ mm Hg}) + (0.75 \cdot 60 \text{ mm Hg}) \]
\[ P_{theoretical} = 25 \text{ mm Hg} + 45 \text{ mm Hg} = 70 \text{ mm Hg} \]

5. **Compare Experimental and Theoretical Vapor Pressures:**
- Given experimental vapor pressure (P) = 75 mm Hg
- Theoretical vapor pressure (P_theoretical) = 70 mm Hg

Since \( P > P_{theoretical} \), this indicates a positive deviation from Raoult's law.

6. **Conclusion:**
- Since the experimental vapor pressure is greater than the theoretical vapor pressure, we conclude that there is a positive deviation from Raoult's law. This implies that the solution behaves in a way that the vapor pressure is higher than expected, indicating weaker intermolecular forces in the mixture compared to the pure components.

### Final Answer:
All the statements regarding the positive deviation from Raoult's law, the lowering of the boiling point, and the weaker forces of attraction between components A and B compared to A-A or B-B interactions are correct.