Question

Which force is responsible for the gas to be held on the surface in Physical adsorption
A. Chemical forces
B. Electrostatic forces
C. Gravitational forces
D. Van Der Waals forces

Answer 1

Hint: Physical adsorption is a simple approach, which attaches the target substance to a chip as a result of hydrogen bonding, van der Waals forces, and hydrophobic interactions. It is also known as Physisorption. In physical adsorption, there are weak van der Waals forces. Therefore, it forms multilayers.

Complete Step by Step Solution:
Physisorption is caused by the intermolecular force that exists between adsorbates and adsorbents. The adsorption is known as van der Waals adsorption since it is caused by the force called van der Waals force. Since van der Waals force exists between adsorbent and adsorbate, physical adsorption can occur on any solid surface.

In chemisorption, adsorbate is attached by a chemical bond. In physical adsorption, the bonding between adsorbent and adsorbate is weak in van der Waal. s bonding which is due to electrostatic forces of attraction between opposite charges. As such multimolecular layers are possible.
Hence the correct option is D.

Note: Physical adsorption phenomenon involves the use of weak Van der Waal forces by means of which gas molecules get adsorbed on a solid surface. It is not specific in nature and hence any gas can be adsorbed onto the surface. Example: Physisorption is the adsorption of gases like hydrogen, nitrogen, etc at lower temperatures on the surface of adsorbent like charcoal.