Question

Which of following forces is responsible for physisorption ?

• A. Coulombic force
• B. Electrostatic force
• C. London force of dispersion
• D. Hydrogen bonding

Hint:

Physisorption involves weak van der Waals forces, namely London dispersion forces.

Answer 1

The Correct Option is C

Step 1: Compare the two types
Physisorption is weak, multilayer, reversible and falls with rising temperature. Chemisorption is strong, monolayer and irreversible.

Step 2: Identify the force
A weak, non-specific attraction between any gas molecule and any surface is the van der Waals attraction, with London dispersion as its main part.

Step 3: Rule out
Coulombic and electrostatic forces need charges, and hydrogen bonds need polar O-H, N-H or F-H, so a general adsorption of gases like $\text{N}_2$ cannot rely on them.

Step 4: Answer
Option (C).

Final Answer:
London dispersion forces cause physisorption. This is option (C). \[ \boxed{\text{(C) }\text{London force of dispersion}} \]