Skip to content
dronacharya.ai
← IIT-JEE 2012 · Paper 2
ChemistryMultiple correct+4Question 36 of 60

IIT-JEE 2012 · Paper 2, Chemistry question 36

The given graphs / data I, II, III and IV represent general trends observed for different physisorption and chemisorption processes under mild conditions of temperature and pressure. Which of the following choice(s) about I, II, III and IV is (are) correct?

Four panels. I: amount adsorbed against T at constant P, decreasing steadily. II: amount adsorbed against T at constant P, rising in an S-shape. III: amount adsorbed against P at 200 K and 250 K, both rising and levelling, the 200 K curve higher. IV: potential energy against distance from the surface, with a small activation barrier E_ads above zero and a deep well of ΔH_ads = 150 kJ mol⁻¹.
Choose one or more options
Answer and worked solution

Official answer: A, C

Reading the graphs.

  • I: the amount adsorbed falls steadily as temperature rises (exothermic, no activation): physisorption.

  • II: the amount first rises with temperature (an activation energy must be overcome) and then falls: chemisorption.

  • III: more is adsorbed at 200 K than at 250 K at every pressure: physisorption.

  • IV: an activation barrier and a deep well of 150 kJ mol⁻¹ (bond-like enthalpy): chemisorption.

  • (A) I physi, II chemi. True.

  • (B) III is not chemisorption. False.

  • (C) IV and II both chemisorption. True.

  • (D) III is not chemisorption. False.

(A), (C)

Topics:Adsorption
← Previous questionNext question →