Which statement/s is/are correct?

Options

A. Physical adsorption is multilayer non-directional and non specifice
B. Chemical adsorption takes more time to attain equilibrium
C. Physical adsrption is due to free valence of atoms
D. Chemical asorption is stronger than physical adsorption

Answer

To determine which statements are correct regarding physical and chemical adsorption, let's analyze each statement step by step.

### Step 1: Analyze Statement A
**Statement A:** Physical adsorption is multi-layer, non-directional, and non-specific.

- **Multi-layer:** Physical adsorption occurs due to weak van der Waals forces, allowing multiple layers of adsorbate to form on the adsorbent.
- **Non-directional:** The forces involved are weak and do not favor a specific orientation of the adsorbate molecules.
- **Non-specific:** There is no specific chemical bonding involved, making it non-specific.

**Conclusion for Statement A:** This statement is **true**.

### Step 2: Analyze Statement B
**Statement B:** Chemical adsorption takes more time to attain equilibrium.

- In chemical adsorption, the adsorbate forms strong chemical bonds with the adsorbent.
- These strong bonds require more energy and time to form, resulting in a longer time to reach equilibrium compared to physical adsorption.

**Conclusion for Statement B:** This statement is **true**.

### Step 3: Analyze Statement C
**Statement C:** Physical adsorption is due to free valence of electrons.

- This statement is incorrect. Physical adsorption is primarily due to weak van der Waals forces, not free valence electrons.

**Conclusion for Statement C:** This statement is **false**.

### Step 4: Analyze Statement D
**Statement D:** Chemical adsorption is stronger than physical adsorption.

- Chemical adsorption involves the formation of strong chemical bonds, which are indeed stronger than the weak van der Waals forces involved in physical adsorption.

**Conclusion for Statement D:** This statement is **true**.

### Final Conclusion
Based on the analysis:
- **Correct Statements:** A, B, and D.
- **Incorrect Statement:** C.

### Summary of Correct Statements
- Statement A: True
- Statement B: True
- Statement C: False
- Statement D: True