Question

Which of the following is an example of physisorption?

• A. Adsorption of \( \text{NH}_3 \) on charcoal
• B. Adsorption of \( \text{H}_2 \) on Ni
• C. Adsorption of noble gases on solid surface
• D. Adsorption of \( \text{O}_2 \) on heated metal

Hint:

Physisorption is non-specific, reversible, and occurs at low temperature; typical for inert gases and weak interactions.

Answer 1

The Correct Option is C

- Physisorption involves weak van der Waals forces. - Noble gases like He, Ne, Ar adsorb onto surfaces via physical forces, without forming chemical bonds. - Others like \( \text{NH}_3 \) or \( \text{O}_2 \) may form chemical bonds — hence show chemisorption. Answer: \( \boxed{\text{Adsorption of noble gases on solid surface}} \)