Surface Chemistry

The characteristic of physisorption that is not correct is:

Enthalpy of adsorption is high.

Physisorption is characterized by weak van der Waals forces between the adsorbent and the adsorbate. As a result, the enthalpy of adsorption in physisorption is relatively low. The other options are correct:

• Physisorption arises because of van der Waals forces.
• Physisorption is not specific in nature.
• Physisorption can result in the formation of multi-molecular layers on the adsorbent surface under high pressure.

Among the options provided, the positively charged sol is Gold Sol.

Gold Sol is a colloidal solution of gold nanoparticles suspended in a liquid medium. It is positively charged due to the adsorption of ions or molecules on the surface of gold nanoparticles, resulting in a positively charged sol.