Which one of the following is not applicable to the phenomenon of adsorption?

Options

A. `Delta H gt 0`
B. `Delta G lt 0`
C. `Delta S lt 0 `
D. `Delta H lt 0`

Explanation

To determine which statement is not applicable to the phenomenon of adsorption, we need to analyze each of the given options regarding Gibbs free energy (ΔG), entropy (ΔS), and enthalpy (ΔH) in the context of adsorption.

### Step-by-step Solution:

1. **Understanding Gibbs Free Energy (ΔG)**:
- For any spontaneous process, the Gibbs free energy change (ΔG) must be less than 0 (ΔG < 0).
- In the case of adsorption, the process is spontaneous, meaning ΔG is indeed less than 0.

2. **Understanding Entropy (ΔS)**:
- Entropy (ΔS) measures the degree of disorder in a system.
- During adsorption, gas molecules transition from a random gaseous state to a more ordered state on the surface of a solid.
- This results in a decrease in disorder, indicating that ΔS is less than 0 (ΔS < 0).

3. **Understanding Enthalpy (ΔH)**:
- Enthalpy (ΔH) reflects the heat content of a system.
- In the context of adsorption, the process typically involves a release of energy (exothermic process), which means that the enthalpy change is negative (ΔH < 0).
- Therefore, ΔH for adsorption is less than 0.

4. **Analyzing the Options**:
- **Option 1**: ΔH > 0 (This suggests an endothermic process, which is not applicable to adsorption).
- **Option 2**: ΔG < 0 (This is applicable as adsorption is spontaneous).
- **Option 3**: ΔS < 0 (This is applicable as disorder decreases during adsorption).
- **Option 4**: ΔH < 0 (This is applicable as adsorption is exothermic).

5. **Conclusion**:
- The only statement that is not applicable to the phenomenon of adsorption is **Option 1: ΔH > 0**.
- Therefore, the answer is **Option 1**.