Which of the following interface cannot be obtained?

Options

A. Liquid-Liquid
B. Solid-Liquid
C. Liquid-Gas
D. Gas-Gas

Answer

To solve the question "Which of the following interfaces cannot be obtained?", we will analyze each option provided to determine if an interface can be formed between the phases mentioned.

### Step-by-Step Solution:

1. **Understanding Interface**:
- An interface is the boundary between two different phases. A phase can be solid, liquid, or gas.

2. **Analyzing Each Option**:
- **Option A: Liquid-Liquid**:
- If two liquids are immiscible (they do not mix), they will form two distinct phases, thus creating an interface.
- **Conclusion**: An interface can be obtained.

- **Option B: Solid-Liquid**:
- A solid and a liquid can coexist, forming a distinct interface between the solid phase and the liquid phase.
- **Conclusion**: An interface can be obtained.

- **Option C: Liquid-Gas**:
- A liquid and a gas can also coexist, forming an interface between the liquid phase and the gas phase.
- **Conclusion**: An interface can be obtained.

- **Option D: Gas-Gas**:
- Gases are generally completely miscible, meaning they mix uniformly and do not form separate phases. Therefore, there is no distinct boundary or interface between them.
- **Conclusion**: An interface cannot be obtained.

3. **Final Answer**:
- Based on the analysis, the option that cannot form an interface is **Option D: Gas-Gas**.