Activated charcoal works by which mechanism to limit absorption of poisons?

• A. Absorption
• B. Ion exchange
• C. Adsorption
• D. Hydrolysis

Answer: (C)

Activated charcoal works by adsorption, meaning it binds toxins to its surface rather than letting them pass into the bloodstream. Its highly porous structure creates a huge surface area, so many molecules of poison adhere to the charcoal particles as they pass through the gastrointestinal tract. This binding keeps the poison from crossing the gut lining and entering the circulation, and the charcoal–poison complex is then excreted in the stool. It isn’t absorbed into the body itself (so it isn’t an absorption process), it doesn’t swap ions with the toxin (not ion exchange), and it doesn’t chemically break substances down via water (not hydrolysis).