SURFACE CHEMISTRY MCQs

By: Prof. Dr. Fazal Rehman | Last updated: May 29, 2025

1. : The catalyst helpful and used in the lead chamber process in the oxidation of SO₂ to SO₃ is
(A) V₂O₅
(B) FeO
(C) Pt
(D) NO

2. : ___ is the substance on whose surface adsorption takes place.
(A) Porous substance
(B) Absorbent
(C) Active substance
(D) Adsorbate

3. : Retarded reaction is that
(A) In which the rate of the reaction is independent of pressure
(B) For which ∆G is positive
(C) Which are reversible under all conditions
(D) In which products are strongly adsorbed on the surface of the solid catalyst

4. : According to the Langmuir isotherm, when the pressure of the gas is very large, the adsorption
(A) Is directly proportional to pressure
(B) Is inversely proportional to pressure
(C) Is independent of pressure
(D) Is directly proportional to the square of the pressure

5. : Which statement is true regarding chemisorption?
(A) It is monolayeric in nature
(B) It is not specific in nature
(C) It is reversible in nature
(D) It occurs at low temperature

6. : Which characteristic of adsorption is not true?
(A) Adsorption, in general, increases with increase in temperature
(B) Adsorption on solids is reversible in nature
(C) Adsorption is normally selective in nature
(D) Both enthalpy and entropy of adsorption are negative

7. : If θ is the fraction of the surface occupied by adsorbate molecules at equilibrium, then according to the Langmuir theory, the rate of condensation is given by
(A) αθρ
(B) αθ
(C) a(1 – θ)
(D) a(1 – θ)p

8. : ___ is the enrichment of chemical substances at the surface of a solid.
(A) Sorption
(B) Isotherm
(C) Adsorption
(D) Absorption

9. : The kinetics of the decomposition of ammonia on the tungsten surface follows
(A) Third order
(B) First order
(C) Second order
(D) Zero order

10. : Which is not true for physical adsorption?
(A) It is reversible
(B) It increases with increase of P
(C) It occurs in the form of multilayer
(D) It needs activation energy

11. : The adsorption theory can explain the action of all these except
(A) Heterogeneous catalysis
(B) Acid-base catalysis
(C) Catalytic poisons
(D) Promoters

12. : Catalytic poisons act by
(A) Making the products inert
(B) Chemical combination with any one of the reactants
(C) Increasing the rate of the backward reaction
(D) Getting adsorbed on active centers on the catalyst surface

13. : Enthalpy change in adsorption is
(A) Positive
(B) Negative
(C) Zero
(D) None of A, B, and C

14. : Adsorption is multilayer in case of
(A) Chemical adsorption
(B) Physical adsorption
(C) Both A & B
(D) Enzyme catalysis

15. : In adsorption of methane on charcoal, charcoal is
(A) Adsorbent
(B) Adsorbate
(C) Catalyst
(D) None of A, B, and C

16. : A catalyst is a substance that
(A) Alters the reaction mechanism
(B) Increases the activation energy
(C) Increases the average K.E. of the reactant molecules
(D) Increases the frequency of collision of reactant molecules

17. : Spontaneous adsorption of gas on solid surface is an exothermic process because
(A) Entropy change decreases for the gas
(B) Entropy change increases for the gas
(C) Enthalpy change increases for the system
(D) Free energy change increases for the gas

18. : The adsorption of a gas by metal is called
(A) Sorption
(B) Physical adsorption
(C) Chemical adsorption
(D) Occlusion

19. : A substance which lowers the catalytic activity of a catalyst is called a/an
(A) Poison
(B) Negative catalyst
(C) Promoter
(D) Auto catalyst

20. : A graph of extent of adsorption vs temperature at constant pressure is called
(A) Adsorption isobar
(B) Adsorption isotherm
(C) Adsorption isostere
(D) None of A, B, and C

21. : Dyeing of cotton is an example of
(A) Adsorption
(B) Sorption
(C) Absorption
(D) None of A, B, and C

22. : Which isotherm model explains chemical adsorption?
(A) Langmuir isotherm
(B) BET isotherm
(C) Freundlich isotherm
(D) None of A, B, and C

23. : In the Langmuir adsorption isotherm, when p → 0, the amount of substance adsorbed per gram of the adsorbent is proportional to
(A) P
(B) 1/p
(C) p²
(D) p°

24. : Pd is a good adsorbent for
(A) CO
(B) H₂
(C) SO₂
(D) CO₂

25. : The Langmuir theory of unimolecular adsorption is normally valid at
(A) Low pressures and low temperatures
(B) High pressures and high temperatures
(C) High pressures and low temperatures
(D) Low pressures and high temperatures

26. : The activity of a catalyst depends upon
(A) Particle size
(B) Mass
(C) Solubility
(D) None of A, B, and C

27. : Simultaneous occurrence of both adsorption and absorption is called
(A) Sorption
(B) Physical adsorption
(C) Chemical adsorption
(D) Occlusion

28. : The heat of adsorption for physical adsorption is normally in what range?
(A) 100–150 kJ
(B) 40–60 kJ
(C) 20–40 kJ
(D) None of A, B, and C

29. : Rate of physical adsorption increases with
(A) Increase in temperature
(B) Decrease in temperature
(C) Decrease in pressure
(D) Decrease in surface area

30. : The extent of adsorption is affected by which factor(s)?
(A) Surface area
(B) Temperature
(C) Pressure
(D) All of A, B, and C

31. : Which catalyst is helpful and used in polymerization of alkenes?
(A) (Ph₃PO)₃RhCl
(B) (Ph₃P)₃RhCl
(C) (C₅H₅)₃Al + TiCl₃
(D) Rh₂O₃

32. : Identify the true statement:
(A) A catalyst accelerates the rate of a chemical reaction
(B) A catalyst cannot start a chemical reaction
(C) A catalyst can retard the rate of a chemical reaction
(D) A catalyst controls the speed of the reaction

33. : A catalyst increases the rate of chemical reaction by
(A) Decreasing activation energy
(B) Decreasing internal energy
(C) Decreasing enthalpy
(D) Increasing activation energy

34. : Organic catalysts differ from the inorganic catalysts in the fact that
(A) They are consumed
(B) They have no difference
(C) They are not much active
(D) They are proteins in nature

35. : Which process does not use a catalyst?
(A) Thermit process
(B) Ostwald process
(C) Haber process
(D) Contact process

36. : Wilkinson catalyst helpful and used in hydrogenation of alkenes is
(A) RhCl₃
(B) (Ph₃PO)₃RhCl
(C) (Ph₃P)₃RhC
(D) Rh₂₂O₃

37. : Which catalyst is helpful and used in the inversion of sucrose?
(A) (C₂H₅)₃Al + TiCl₃
(B) Pt
(C) Xymase
(D) Invertase

38. : Which is less than zero during adsorption?
(A) Enthalpy change
(B) Free energy change
(C) Entropy change
(D) All of A, B, and C

39. : For the adsorption of gas on a solid surface, the plot of log(x/m) vs. log P is linear with slope equal to
(A) log k
(B) n
(C) k
(D) 1/n

40. : In physical adsorption, what are the forces that are associated?
(A) van der Waals forces
(B) Covalent forces
(C) H-bonding
(D) Ionic forces

41. : For the adsorption of gas on a solid surface, which statement is not true?
(A) It is a reversible process
(B) Enthalpy change is negative
(C) Entropy change is negative
(D) Adsorption increases with increase in temperature

42. : Adsorption is accompanied by
(A) Decrease in the free energy of the system
(B) TΔS value for the process to be positive
(C) Increase in the entropy of the system
(D) Increase in the enthalpy of the system

43. : The heat of adsorption for chemical adsorption is normally in what range?
(A) 20–40 kJ
(B) 1000–1500 kJ
(C) 40–400 kJ
(D) None of A, B, and C

44. : A graph of extent of adsorption vs pressure at constant temperature is called
(A) Adsorption isotherm
(B) Adsorption isobar
(C) Adsorption isostere
(D) None of A, B, and C

45. : The activation energy of a chemical reaction is lowered by
(A) Adding a catalyst
(B) Decreasing the temperature
(C) Increasing the temperature
(D) Decreasing the potential energy