During adsorption

Options

A. `T Delta S ` is positive
B. `Delta H - T Delta S ` is negative
C. `DeltaH ` is positive
D. `T Delta S ` and `DeltaG ` becomes zero

Explanation

To solve the question regarding the duration of adsorption and its spontaneity, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Adsorption**:
- Adsorption is the process where molecules from a gas or liquid phase adhere to a solid surface. This process is generally spontaneous.

**Hint**: Remember that spontaneous processes occur without external intervention.

2. **Gibbs Free Energy Equation**:
- The spontaneity of a process can be determined using the Gibbs Helmholtz equation:
\[ \Delta G = \Delta H - T \Delta S \]
- Where:
- \(\Delta G\) = change in free energy
- \(\Delta H\) = change in enthalpy
- \(T\) = temperature (in Kelvin)
- \(\Delta S\) = change in entropy

**Hint**: This equation helps us understand the relationship between enthalpy, entropy, and free energy.

3. **Criteria for Spontaneity**:
- For a process to be spontaneous, \(\Delta G\) must be negative. This means:
\[ \Delta H - T \Delta S < 0 \]
- Rearranging gives:
\[ \Delta H < T \Delta S \]

**Hint**: A negative \(\Delta G\) indicates that the process is favorable and can occur naturally.

4. **Understanding Enthalpy and Entropy**:
- In the context of adsorption:
- \(\Delta H\) is typically negative (exothermic process).
- \(\Delta S\) can be negative or positive depending on the system, but for adsorption, it often decreases because the gas molecules become more ordered when they adhere to a surface.

**Hint**: Exothermic processes (negative \(\Delta H\)) are often associated with spontaneous adsorption.

5. **Conclusion from Options**:
- According to the problem, we need to identify when \(\Delta H - T \Delta S\) is negative.
- The correct option states that \(\Delta H - T \Delta S < 0\), which aligns with our understanding of spontaneous adsorption processes.

**Hint**: Look for options that indicate a negative value for \(\Delta G\) or the condition for spontaneity.

### Final Answer:
The correct answer is **Option B**, which states that \(\Delta H - T \Delta S\) is negative, indicating that the adsorption process is spontaneous.