Compreshension-II
In non-ideal solutions, at one of the intermediate compostions, the total vapour pressure is highest and the boiling point is lowest. At this point, the composition of the liquid and vapour phase is same. So, if liquid mixture vapouriese at this point and vapours are condensed, teh condensate contains same compositon as present in original liquid mixture. it means at this point liquid behaves like a pure liquid and is called an Azeotropic mixture.
Choose the correct answer :

Options

A. Ideal solutions cannot be separated into their components by fractional distillation
B. For ideal solutions enthalpy of mixing is always greater than zero
C. Only non-ideal solution showing positive deviation cannot be separated out by fraction distillation
D. Non-ideal solution showing both positive and negative deviation cannot be separated out by fractional distillation

Answer

To solve the question regarding azeotropic mixtures in non-ideal solutions, we will analyze the characteristics of azeotropes and the options provided.

### Step-by-Step Solution:

1. **Understanding Azeotropic Mixtures**:
- Azeotropic mixtures are specific mixtures of liquids that boil at a constant temperature and maintain the same composition in both the liquid and vapor phases during boiling. This means that when they vaporize, the vapor has the same composition as the liquid.

2. **Characteristics of Azeotropes**:
- In non-ideal solutions, azeotropic mixtures can occur due to deviations from Raoult's law. These deviations can be either positive or negative.
- Azeotropes cannot be separated into their components by simple distillation because they behave like a single substance.

3. **Analyzing the Options**:
- **Option 1**: "Ideal solution cannot be separated."
- This is incorrect because ideal solutions can be separated by distillation, and they do not form azeotropes.
- **Option 2**: "Change in enthalpy is zero in ideal solutions."
- This statement is true for ideal solutions but does not relate to azeotropic behavior, so it is not the correct answer.
- **Option 3**: "Only non-ideal solutions showing positive deviation cannot be separated."
- This is incorrect because both positive and negative deviations can lead to azeotropes, which cannot be separated.
- **Option 4**: "Non-ideal solutions showing both positive and negative deviation cannot be separated by fractional distillation."
- This is the correct answer. Azeotropic mixtures cannot be separated by fractional distillation due to their unique boiling characteristics.

4. **Conclusion**:
- The correct answer is **Option 4**: Non-ideal solutions showing both positive and negative deviation cannot be separated by fractional distillation.