Adsorption is the phenomenon in which a substance

Options

A. accumulates on the surface of the other substance
B. goes into the body of the other substance
C. remains close to the other substance
D. oxidises or reduces the other substance

Answer

**Step-by-Step Solution:**

1. **Understanding Adsorption**:
- Adsorption is a surface phenomenon where molecules of a gas, liquid, or dissolved solid accumulate on the surface of a solid or liquid (known as the adsorbent).
- This accumulation results in a higher concentration of the adsorbate (the substance being adsorbed) at the surface compared to its concentration in the bulk phase.

2. **Mechanism of Adsorption**:
- The process occurs due to the presence of unbalanced or residual forces at the surface of the adsorbent. These forces attract the molecules of the adsorbate to the surface.

3. **Examples of Adsorption**:
- Common examples include:
- The adsorption of gases by charcoal.
- The adsorption of dyes by charcoal.

4. **Analyzing the Options**:
- Option 1 states that adsorption is the phenomenon in which a substance accumulates molecules of gas, liquid, or dissolved solid particles onto the surface. This is correct because it describes the accumulation of adsorbate on the adsorbent surface.
- Option 2 suggests that the substance goes into the body of another substance, which is incorrect as adsorption does not involve penetration into the bulk.
- Option 3 states that the substance remains close to the other substance, which is also incorrect since adsorption specifically refers to the accumulation on the surface.
- Option 4 claims that it oxidizes or reduces the other substance, which is not relevant to the definition of adsorption.

5. **Conclusion**:
- Based on the analysis, the correct answer is Option 1, as it accurately describes the process of adsorption.

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