The number of statement/s which are the characteristics of physisorption is ________
A. It is highly specific in nature
B. Enthalpy of adsorption is high
C. It decreases with increase in temperature
D. It results into unimolecular layer
E. No activation energy is needed
A. It is highly specific in nature
B. Enthalpy of adsorption is high
C. It decreases with increase in temperature
D. It results into unimolecular layer
E. No activation energy is needed
Show answer and solution
Answer: 2
Solution
Physisorption characteristics: it is NOT highly specific (A is wrong), enthalpy is LOW ~20-40 kJ/mol (B is wrong), it DECREASES with increase in temperature because it is exothermic and reversible (C is CORRECT), it results in MULTILAYER adsorption not unimolecular (D is wrong), and NO activation energy is needed since it involves weak van der Waals forces (E is CORRECT). So exactly 2 statements (C and E) correctly describe physisorption.
[JEE Main 2023 · 24 Jan · Shift 2]