A mixture of two completely miscible non-ideal liquids which distil as such without change in its composition at a constant temperature as though it were a pure liquid. This mixture is known as:

Options

A. Binary liquid mixture
B. Azeotropic mixture
C. Eutectic mixture
D. Ideal mixture

Answer

To solve the question regarding the mixture of two completely miscible non-ideal liquids that distill without a change in composition at a constant temperature, we can follow these steps:

### Step 1: Understand the Concept of Miscibility
- Miscibility refers to the ability of two substances to mix in all proportions without separating into two phases. In this case, we are dealing with two liquids that are completely miscible.

**Hint:** Consider the definition of miscibility and how it applies to liquids.

### Step 2: Identify Non-Ideal Solutions
- Non-ideal solutions are those that do not obey Raoult's law. This means that the interactions between the molecules of the different components are not the same as those in the pure components.

**Hint:** Recall what makes a solution non-ideal and how it differs from an ideal solution.

### Step 3: Recognize the Distillation Behavior
- The question states that the mixture distills as if it were a pure liquid at a constant temperature. This indicates that the vapor composition is the same as the liquid composition during distillation.

**Hint:** Think about what it means for a mixture to behave like a pure substance during distillation.

### Step 4: Define the Mixture
- A mixture that distills without a change in composition at a constant temperature is known as an **azeotrope**. An azeotropic mixture has a specific boiling point and composition that cannot be altered by simple distillation.

**Hint:** Recall the term used for mixtures that maintain their composition during distillation.

### Final Answer
The mixture is known as an **azeotrope**.