In a mixture of A and B components show negative deviation when

Options

A. A-B interaction is stronger than A-A and B-B interaction
B. A-B interaction is weaker than A-A and B-B interaction
C. `DeltaV_(mix) gt 0, DeltaS_(mix) gt 0`
D. `DeltaV_(mix) = 0, DeltaS_(mix) gt 0`

Answer

To solve the question regarding when a mixture of components A and B shows negative deviation, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Ideal vs Non-Ideal Solutions**:
- An ideal solution is one where the interactions between like molecules (A-A and B-B) are equal to the interactions between unlike molecules (A-B). In such cases, the properties like enthalpy of mixing (ΔH) and volume of mixing (ΔV) are zero.
- Non-ideal solutions can show either positive or negative deviations from ideal behavior.

2. **Characteristics of Negative Deviation**:
- In a non-ideal solution showing negative deviation, the interactions between unlike molecules (A-B) are stronger than the interactions between like molecules (A-A and B-B).
- This means:
- A-B interaction > A-A interaction
- A-B interaction > B-B interaction
- As a result, the enthalpy of mixing (ΔH) and the volume of mixing (ΔV) are both less than zero (ΔH < 0 and ΔV < 0).
- The entropy of mixing (ΔS) is still greater than zero (ΔS > 0) because the randomness increases.

3. **Evaluating the Options**:
- The question provides four options regarding the interactions in the mixture:
1. A-B interaction is stronger than A-A and B-B interactions.
2. A-B interaction is weaker than A-A and B-B interactions.
3. ΔV of mixture is greater than 0 and ΔS of mixture is greater than 0.
4. ΔV of mixing is equal to 0 and ΔS of mixture is greater than 0.
- Based on our understanding of negative deviation:
- **Option 1** is correct: A-B interaction is stronger than A-A and B-B interactions, which is the characteristic of negative deviation.
- **Option 2** is incorrect as it describes positive deviation.
- **Option 3** is incorrect as it describes positive deviation characteristics.
- **Option 4** describes an ideal solution, which is also incorrect.

4. **Conclusion**:
- Therefore, the correct answer to the question is **Option 1**: A-B interaction is stronger than A-A and B-B interactions.