Which of the following are the characteristics of chemisorptin ?
1. High heat of adsorption
2. Irreversibility
3. Low activation energy
Select the correct answer using the code given below :

Options

A. 1 and 2 only
B. 1 and 3 only
C. 2 and 3 only
D. 1, 2 and 3

Explanation

To determine the characteristics of chemisorption, we need to analyze each of the given statements:

1. **High heat of adsorption**: Chemisorption involves the formation of strong chemical bonds between the adsorbate and the surface of the adsorbent. This process is exothermic, meaning it releases heat. Therefore, chemisorption is characterized by a high heat of adsorption. This statement is **true**.

2. **Irreversibility**: Chemisorption typically involves a chemical change, which means that once the adsorbate is bonded to the surface, it cannot easily be removed without breaking the chemical bond. This makes chemisorption an irreversible process. Thus, this statement is also **true**.

3. **Low activation energy**: Chemisorption generally requires a significant amount of energy to break existing bonds and form new chemical bonds. Therefore, it is characterized by high activation energy rather than low activation energy. This statement is **false**.

Now, summarizing the true statements:
- Statement 1 (High heat of adsorption): True
- Statement 2 (Irreversibility): True
- Statement 3 (Low activation energy): False

Based on this analysis, the correct answer is that the characteristics of chemisorption include statements 1 and 2.

**Final Answer**: The correct answer is option 1 and 2.