Which are not purely surface phenomena?

Options

A. Adsorption , surface tension
B. surface tension , viscosity
C. Adsorption , viscosity
D. Absorption , viscosity

Answer

To determine which phenomena are not purely surface phenomena, we need to analyze the options provided in the question. Let's break down the concepts involved:

### Step-by-Step Solution

1. **Understanding Adsorption**:
- Adsorption is the process where molecules adhere to the surface of a solid or liquid. This occurs due to unbalanced or residual forces at the surface.
- **Conclusion**: Adsorption is a surface phenomenon.

2. **Understanding Surface Tension**:
- Surface tension is the cohesive force between liquid molecules at the surface of a liquid. It results from the attraction between molecules and is responsible for the behavior of liquids at their interfaces.
- **Conclusion**: Surface tension is also a surface phenomenon.

3. **Understanding Viscosity**:
- Viscosity measures a fluid's resistance to flow. It is a property that describes how thick or thin a fluid is and is influenced by the interactions between molecules throughout the entire volume of the fluid.
- **Conclusion**: Viscosity is a bulk property and not purely a surface phenomenon.

4. **Understanding Absorption**:
- Absorption refers to the process where molecules are assimilated throughout the bulk of a solid or liquid medium. This means that the molecules penetrate into the entire volume rather than just adhering to the surface.
- **Conclusion**: Absorption is also a bulk phenomenon.

5. **Identifying the Correct Options**:
- Now we can analyze the options:
- **Option 1**: Adsorption and Surface Tension - Both are surface phenomena.
- **Option 2**: Surface Tension and Viscosity - Surface tension is a surface phenomenon, but viscosity is not.
- **Option 3**: Adsorption and Viscosity - Adsorption is a surface phenomenon, but viscosity is not.
- **Option 4**: Absorption and Viscosity - Both are not purely surface phenomena.

6. **Final Answer**:
- The correct answer is **Option 4: Absorption and Viscosity**, as both are not purely surface phenomena.