Which statement regarding sorption is false?

• A. Adsorption occurs when fumigant molecules adhere to the surface of a treated material.
• B. Absorption occurs when the molecules penetrate the material.
• C. As a rule, sorption is greater at warm temperatures.
• D. Sorption reduces the effectiveness of fumigants by removing molecules from the air.

Answer: (C)

Sorption includes two processes: adsorption, where fumigant molecules cling to a surface, and absorption, where molecules diffuse into the material. Temperature plays a big role: most sorption of fumigants to materials is greater at lower temperatures because these interactions are typically exothermic—heat helps drive molecules back into the air, so increasing temperature tends to reduce sorption. That means the idea that sorption is greater at warm temperatures is false. By removing fumigant molecules from the air, sorption lowers the amount available to act on pests, reducing effectiveness. The definitions of adsorption (surface adhesion) and absorption (penetration into the material) are correct, and sorption’s impact on air concentration explains why it diminishes fumigant performance.