Which of the following shows positive deviation from Raoult's law ?

Options

A. `C_(6)H_(6) and C_(6)H_(5)CH_(3)`
B. `C_(^)H_(6) and C Cl_(4)`
C. `ChCl_(3) and C_(2)H_(3)OH`
D. `CHCl_(3) and CH_(3)COCH_(3)`

Answer

To determine which of the given options shows positive deviation from Raoult's law, we need to understand the concept of positive deviation and the interactions involved in liquid mixtures.

### Step-by-Step Solution:

1. **Understanding Raoult's Law**:
Raoult's law states that the partial vapor pressure of each component in an ideal solution is directly proportional to its mole fraction in the solution. For an ideal solution, the vapor pressure of the mixture is equal to the sum of the partial pressures of each component.

2. **Defining Positive Deviation**:
Positive deviation occurs when the vapor pressure of the solution is greater than what is predicted by Raoult's law. This typically happens when the interactions between different molecules (A and B) in the mixture are weaker than the interactions between the same molecules (A-A and B-B).

3. **Analyzing Interactions**:
In a mixture showing positive deviation, the intermolecular forces between different components (A and B) are weaker than the forces between the same components. This leads to an increase in vapor pressure because the molecules escape into the vapor phase more easily.

4. **Identifying the Correct Option**:
To identify which option shows positive deviation, we need to consider the nature of the interactions in the mixtures provided in the options. If the mixture involves components that have strong hydrogen bonding when alone (like A-A or B-B), but weaker interactions when mixed (A-B), it is likely to show positive deviation.

5. **Conclusion**:
Based on the analysis of interactions, the correct answer is option C. This option likely involves components that have strong hydrogen bonding in their pure states, but when mixed, the interactions are not strong enough to maintain the same level of bonding, leading to positive deviation from Raoult's law.