Select the correct statement

Options

A. Longmuir adsorption is highly specific
B. Van der Waals adsorption is reversible
C. Both A and B are exothermic
D. All are correct

Answer

To solve the question regarding the correct statement about adsorption, let's analyze each statement one by one:

### Step 1: Analyze Statement 1
**Statement 1:** "Langmuir adsorption is highly specific."
- Langmuir adsorption is indeed characterized by its specificity. It describes a process where the adsorbate molecules form a monolayer on the adsorbent surface, and this process is dependent on specific conditions such as temperature and pressure. Therefore, this statement is **correct**.

### Step 2: Analyze Statement 2
**Statement 2:** "Van der Waals adsorption is reversible."
- Van der Waals forces are weak intermolecular forces that govern physical adsorption (also known as physisorption). Because these forces are weak, the adsorbate can easily detach from the adsorbent, making this process reversible. Thus, this statement is also **correct**.

### Step 3: Analyze Statement 3
**Statement 3:** "Both are exothermic."
- Both physical adsorption (physisorption) and chemical adsorption (chemisorption) release energy when the adsorbate adheres to the adsorbent. This means that both processes are exothermic. Hence, this statement is **correct**.

### Step 4: Analyze Statement 4
**Statement 4:** "All are correct."
- Since we have established that Statements 1, 2, and 3 are all correct, it follows that Statement 4, which claims that all previous statements are correct, is also **correct**.

### Conclusion
The correct answer is **Statement 4: All are correct**.

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