Solutions which distil without any change in composition and temperature are called:

Options

A. Ideal
B. Super saturated
C. Azeotropic mixture
D. Isotonic

Explanation

To solve the question "Solutions which distil without any change in composition and temperature are called:", we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks about a specific type of solution that distills without any change in composition and temperature.

2. **Identifying Key Terms**: The key phrases in the question are "distil without any change" and "composition and temperature". This suggests we are looking for a solution that maintains its properties during the distillation process.

3. **Defining Azeotropic Mixtures**: Azeotropic mixtures are special types of solutions that have a constant boiling point and maintain the same composition in both the liquid and vapor phases during distillation. This means that when they are heated, they will boil and vaporize at a specific temperature without changing their composition.

4. **Characteristics of Azeotropes**: Azeotropic mixtures cannot be separated into their components by simple distillation because the vapor produced has the same composition as the liquid mixture. This is a crucial characteristic that aligns with the question.

5. **Conclusion**: Based on the definition and characteristics of azeotropic mixtures, we conclude that the solutions which distill without any change in composition and temperature are indeed called **azeotropic mixtures**.

### Final Answer:
The correct answer is **azeotropic mixtures**.

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