What is adsorption?

• A. The binding to a surface
• B. The growth of bacteria
• C. The process of binding or sticking to a surface.
• D. The process of aeration

Answer: (C)

Adsorption is the process by which molecules adhere to a solid surface, accumulating at the interface rather than entering the bulk of a material. This surface-bound attraction can be physical (van der Waals forces) or chemical (strong chemical bonds) and is widely used in wastewater treatment to remove contaminants with materials like activated carbon.

The best description here is the process of binding or sticking to a surface, because it captures both the action (binding) and the location (a surface) and treats adsorption as a ongoing process that concentrates substances at the interface. The other ideas—a one-time binding, bacterial growth, or introducing air—do not describe adsorption.