Answer the question on the basis of the passage given below:

Adsorption is a surface phenomenon and it differs from absorption which occurs throughout the body of the substance which absorbs. In physisorption, the attractive forces are mainly van der Waal forces while in chemisorption actual bonding occurs between the particles of adsorbent and adsorbed more easily on the surface of a solid as compared to the gases which are liquified with difficulty. Adsorption increases with increase in pressure and decreases as the temperature is increased.

Which of the following is wrong about chemisorption?

It is reversible in nature

The correct answer is option 4. It is reversible in nature.

The incorrect statement is : It is reversible in nature. 

Here's why:

Chemisorption: This process involves chemical bonds forming between the adsorbate (gas molecule) and the surface atoms of the adsorbent (solid). These bonds are typically stronger than the weak forces involved in physisorption (physical adsorption).

Key characteristics of chemisorption:

1. Formation of compounds: Indeed, when the adsorbate and adsorbent atoms share electrons to form chemical bonds, new compounds are created on the surface. This differentiates chemisorption from physisorption, where the original molecules remain intact.
2. Specificity: Chemisorption often exhibits specificity, meaning certain adsorbates are more likely to form bonds with specific surfaces due to their electronic configurations and geometric compatibility.
3. Temperature dependence: Chemisorption initially increases with increasing temperature as more collisions occur between adsorbate and adsorbent molecules. However, excessively high temperatures can break the newly formed chemical bonds, leading to a decrease in adsorption.
4. Reversibility: Unlike physisorption, which is generally reversible (adsorbate molecules readily desorb with decreasing pressure or temperature), chemisorption usually involves stronger bonds and is not readily reversible. The energy required to break the chemical bonds often makes desorption difficult, making chemisorption an irreversible process under typical conditions.

Therefore, while the other options correctly depict features of chemisorption, the reversibility statement is inaccurate. Chemisorption typically does not reverse easily due to the strong chemical bonds involved.