The accumulation of molecular species at the surface rather than in the bulk of a solid or liquid is termed as

Options

A. absorption
B. adsorption
C. catalysis
D. osmosis

Answer

To solve the question, "The accumulation of molecular species at the surface rather than in the bulk of a solid or liquid is termed as?", we need to analyze the given options and understand the definitions of the terms involved.

### Step-by-Step Solution:

1. **Understanding the Question**:
The question asks for a term that describes the accumulation of molecules at the surface of a solid or liquid, rather than within its bulk.

2. **Analyzing the Options**:
- **Option 1: Absorption**:
- Definition: Absorption is a process where molecules penetrate into the bulk of a material. For example, when a sponge absorbs water, the water molecules move into the sponge's interior.
- Conclusion: This does not fit the question since it refers to accumulation in the bulk, not at the surface.

- **Option 2: Adsorption**:
- Definition: Adsorption is the process where molecules adhere to the surface of a solid or liquid. For example, when water vapor condenses on a cold glass surface, the water molecules accumulate on the surface rather than entering the glass.
- Conclusion: This matches the question perfectly as it refers to accumulation at the surface.

- **Option 3: Catalysis**:
- Definition: Catalysis involves the acceleration of a chemical reaction by a substance called a catalyst. It does not specifically refer to the accumulation of molecules at a surface.
- Conclusion: This option is irrelevant to the question.

- **Option 4: Osmosis**:
- Definition: Osmosis is the movement of solvent molecules through a semi-permeable membrane from a region of low solute concentration to a region of high solute concentration. This process does not relate to the accumulation of molecules at a surface.
- Conclusion: This option is also irrelevant to the question.

3. **Final Conclusion**:
After analyzing all the options, the correct term that describes the accumulation of molecular species at the surface rather than in the bulk is **Adsorption** (Option 2).

### Final Answer:
**Adsorption**