Adsorption phenomenon involves
(A) residual attraction forces
(B) a spontaneous phenomenon
(C) a gaseous adsorbent 

Options

A. A and C are correct
B. B and C are correct
C. A and B are correct
D. A, B and C are all correct

Answer

To solve the question regarding the adsorption phenomenon, we need to evaluate each of the statements provided:

### Step 1: Analyze Statement A
**Statement A: Residual attraction forces**
- Adsorption occurs due to the attraction between the adsorbate (the substance being adsorbed) and the surface of the adsorbent (the material on which adsorption occurs).
- Molecules in the bulk of a material experience balanced forces from surrounding molecules, leading to a net force of zero. However, molecules at the surface experience unbalanced forces because they are only attracted to other molecules on one side.
- These unbalanced forces are referred to as residual attraction forces, which indeed play a crucial role in the adsorption process.
- **Conclusion**: Statement A is correct.

### Step 2: Analyze Statement B
**Statement B: A spontaneous phenomenon**
- Adsorption is generally a spontaneous process. This means that it occurs naturally without the need for external energy input.
- In thermodynamic terms, a process is spontaneous if the change in Gibbs free energy (ΔG) is negative. For adsorption, ΔG is typically negative, indicating that the process occurs spontaneously.
- **Conclusion**: Statement B is correct.

### Step 3: Analyze Statement C
**Statement C: A gaseous adsorbent**
- The term "adsorbent" refers to the material that adsorbs the substance (adsorbate). Adsorbents can be solids or liquids, but they are not gases.
- Gases can act as adsorbates (the substances being adsorbed), but they cannot be adsorbents themselves.
- **Conclusion**: Statement C is incorrect.

### Final Conclusion
Based on the analysis:
- Statement A is correct.
- Statement B is correct.
- Statement C is incorrect.

Thus, the correct answer is that the adsorption phenomenon involves statements A and B.

### Answer:
**A and B are correct; C is incorrect.**

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