Which of the following is a heterogeneous mixture?

Options

A. milk
B. common salt
C. sugar
D. carbon dioxide

Answer

To determine which of the following is a heterogeneous mixture, we need to analyze the options provided: milk, common salt, sugar, and carbon dioxide.

### Step-by-Step Solution:

1. **Understand the Definition of a Mixture**:
- A mixture is formed when two or more substances are combined together. The key point is that the substances retain their individual properties.

2. **Differentiate Between Homogeneous and Heterogeneous Mixtures**:
- A homogeneous mixture has a uniform composition throughout, meaning you cannot distinguish the different components.
- A heterogeneous mixture has a non-uniform composition, where the different components can be seen and separated.

3. **Analyze Each Option**:
- **Option 1: Milk**:
- Milk is a mixture of fats and water. The fats do not dissolve completely in water, leading to a non-uniform composition. Therefore, milk is a heterogeneous mixture.
- **Option 2: Common Salt (NaCl)**:
- Common salt is a pure compound. It has a uniform composition and does not contain different components that can be separated.
- **Option 3: Sugar (C12H22O11)**:
- Sugar is also a pure compound with a uniform composition. It does not form a mixture.
- **Option 4: Carbon Dioxide (CO2)**:
- Carbon dioxide is a pure compound as well. It has a uniform composition and does not exhibit the characteristics of a mixture.

4. **Conclusion**:
- Among the options provided, only milk is a heterogeneous mixture. The other options (common salt, sugar, and carbon dioxide) are pure compounds.

### Final Answer:
The correct answer is **Option 1: Milk**.