The accumulation of molecular species at the surface rather than in the bulk of a solid or liquid is termed as adsorption. There are two types of adsorption. In physisorption, attractive forces are mainly van der Waals while in chemical adsorption adsorbate is held with chemical bonds adsorbent. Adsorption increases with increase in pressure and decrease as temperature is increased.

Which of the following is not application of adsorption?

Inversion of cane sugar using mineral acids as catalysts

 The correct answer is (4) Inversion of cane sugar using mineral acids as catalysts.

Inversion of cane sugar using mineral acids as catalysts is a chemical reaction, not an adsorption process. Adsorption is a physical process in which molecules of a gas or liquid adhere to the surface of a solid.

Therefore, the answer is (4).

The other options are all applications of adsorption:

• Control of humidity using silica gel: Silica gel is a porous solid that has a high affinity for water molecules. It is used in desiccators and other devices to remove moisture from the air.
• Separation of noble gases using charcoal: Charcoal has a high affinity for noble gas molecules. It is used to separate noble gases from other gases, such as air.
• Removal of colouring matter from solutions: Activated charcoal is a type of charcoal that has been treated to increase its surface area. It is used to remove impurities, such as coloring matter, from solutions.

Adsorption is a very versatile process and has many applications in industry, medicine, and environmental technology.