CHEMICAL KINETICS – 3

1) In which of the following is platinum is not used as a catalyst?
a)
b)
c) Oxidation of NH3 to NO
d)

2) Which of the following is an example of autocatalysis?
a)
b) Oxidation of oxalic acid with KmnO4 in acid medium
c)
d) Hydrogenation of vegetable oils using Ni catalyst

3) In which of the following reactions is a catalyst required?
a)
b)
c)
d) All

4) Which of the following statements is not true in the case of a catalyst?
a) The catalyst is unchanged chemically at the end of a reaction
b) The catalyst accelerates the reaction
c) In a reversible reaction, the catalyst alters the equilibrium position
d) A small amount of catalyst is sufficient to bring a reaction change

5) Among the following chemical reactions, the one representing homogeneous catalysis is
a)
b)
c)
d)

6) Which of the following does not apply to catalytic reactions?
a) Capability to initiate the non feasible reaction
b) Specificity
c) Lowering the activation energies of forward as well as backward reaction
d)

7) Any substance, which completely destroys or reduces the activity of the catalyst, is called a/an
a) Catalyst
b) Inhibitor
c) Promoter
d) Catalyst poison

8) An auto catalyst is
a) A catalyst for a catalyst
b) One which starts a reaction
c) One of the products of the reaction which acts as a catalyst
d) That which retards a chemical reaction

9) Which of the following types of materials form effective catalysts?
a) Alkali metals
b) Transition metals
c) Alkaline earth metals
d) Radioactive metals

10) Which of the following statements about a catalyst is true?
a) It accelerates the reaction by bringing down free activation energy
b) It does not take part in the reaction mechanism
c)
d) It makes the equilibrium constant more favourable for the forward reaction

11) The efficiency of an enzyme in catalysing a reaction is due to its capacity
a) To form a strong enzyme substrate complex
b) To decrease the bond energy of all substrate molecules
c) To change the shape of the substrate molecule
d) To lower the activation energy of the reaction

12) Which of the following statements is universally correct for a catalyst?
a) A catalyst remains unchanged at the end of chemical reaction
b) A catalyst takes part in a chemical reaction
c) All kinds of catalysts undergo catalytic poisoning
d) A catalyst physically changes at the end of reaction

13) Which of the following acts as a negative catalyst?
a) Lead tetraethyl as antiknock compound
b)
c) Ethanol in oxidation of chloroform
d) All are correct

14) A substance, which promotes the activity of a catalyst, is known as a/an
a) Initiator
b) Catalyst
c) Promoter
d) Auto catalyst

15) Which is not correct regarding a catalyst?
a) Accelerates the rate of reaction in both directions
b) It changes the enthalpy of reaction
c) Reduces the energy of activation of reaction
d) Is specific in nature

16) The catalyst used in the manufacture of HNO3 by Ostwalds process is
a) Rh
b) Pt-Rh
c) Pd
d) Fe

17) Which one is false in the following statement?
a) A catalyst is specific in its action
b) A very small amount of catalyst alters the rate of reaction
c) The number of free valencies on the surface of the catalyst increases on subdivision
d)

18) Platinum is used as a catalyst in the process of
a)
b) Hardening of oil
c) Synthesis of methane
d) Production of synthetic rubber

19) Which of the following is not true about a heterogeneous catalyst?
a) The catalyst and the reactants are in different states
b) The catalyst remains unaffected after the completion of the reaction
c) The catalyst lowers the energy of activation
d) The catalyst changes the equilibrium constant

20) In which of the following processes is a catalyst is not used?
a)
b) Solvay process
c) Lead chamber process
d)

21) When KClO3 is heated, it decomposes into KCl and O2. If some Mn02 is added, the reaction goes much faster because
a)
b)
c)
d) None

22) Which of the following is used to retard the oxidation of chloroform?
a)
b)
c) Glycerol
d)

23) Which of the following is an anti-catalyst to finely divided Fe in Haber process for the manufacture of NH3?
a)
b) NO
c) CO
d)

24) Which of the following is an anti-catalyst to platinum, which is used as a catalyst in the manufacture of H2SO4 by contact process?
a) Arsenious oxide
b)
c) CO
d) V2O5

25) The reaction rate at a given temperature is slower when the
a) Activation energy is higher
b) Activation energy is lower
c) Entropy changes
d) Initial concentration of reactants remains constant

26) Which of the following is a heterogeneous catalysis?
a)
b)
c)
d)

27) Enzymes are known to increase the rate of reaction by factors of
a)
b)
c) 10
d)

28) Enzymes are
a) Substances made by chemists to activate washing powder
b) Very active vegetable catalysts
c) Catalysts found in organisms
d) Synthetic catalysts

29) Which of the following type of catalysis can be explained by the adsorption theory?
a) Homogeneous catalysis
b) Acid-base catalysis
c) Heterogeneous catalysis
d) Enzyme catalysis

30) Which statement is wrong?
a)
b)
c) Hydrogenation of oils requires iron as catalyst
d)

31) The enzyme, which can catalyse the conversion of glucose to ethanol, is
a) Zymase
b) Invertase
c) Maltase
d) Diastase

32) The minimum energy level necessary to permit a reaction to occur is called the
a) Internal energy
b) Threshold energy
c) Activation energy
d) Free energy

33) The catalyst iron, used in the Haber process contains Mo, the function of which is
a) To increase the rate of combination of gases
b) To counterbalance for the presence of impurities in the gas
c) To act as a catalyst promoter and increase activity of catalyst
d) To make up the adverse temperature and pressure conditions

34) A catalyst
a) Increases free energy change in the reaction
b) Decreases the free energy change in reaction
c) Does not increase/decrease the free energy change in the reaction
d) Can either increase/decrease the free energy change, depending on the nature of the catalyst

35) Which of the following statements is wrong?
a) The catalyst does not alter the equilibrium of a reaction
b) A reaction with a higher activation energy has a higher rate constant
c) In the exothermic reaction, the activation energy of the reverse reaction >forward reaction
d) The half life period of a first order reaction is independent of the initial concentration

36) Catalytic poisons are usually the same as
a) Poisons for the human body
b) Enzymes for the human body
c) Vitamins for the human body
d) None

37) The rate of a certain biochemical reaction, when enzyme-catalysed in the human body, is104 times-faster than when it is carried out in the laboratory. The activation energy of this reaction
a) Is zero
b) Is different in both cases
c) Is the same in both the cases
d) Can only be determined if temperature of the reaction is known

38) Platinised asbestos used as a catalyst in the manufacture of H2SO4 is an example of a/an
a) Heterogeneous catalyst
b) Auto catalyst
c) Homocatalyst
d) Induced catalyst

39) A catalyst increases the rate of reaction because it
a) Increases the activation energy
b) Decreases the energy barrier for reaction
c) Decreases the collision diameter
d) Increases the temperature coefficient

40) Zeolites are:
a) Water softeners
b) Catalysts
c) Both
d) None

41) Solid catalysts involve the formation of an activated complex of lower potential energy, thereby providing a more favourable reaction mechanisms. The reasons for the effectiveness of surface catalysts are
a) Adsorption at the surface increases as the concentration of the reacting molecule increases.
b) Adsorption weakens the bonds with in the reacting molecules
c) Adsorption produces a more favourable orientation of the reacting molecules
d) All of these

42) Which of the following is an example of catalyst poison?
a) Addition of antioxidants in rubber
b) Antiknock agents in petrol
c)
d)

43) Consider the reaction
, It is correct to conclude that

a) A catalyst is characterised by selectivity
b) Different surface catalysts have different energy requirements
c) Dehydration and oxidation reactions involve different mechanisms
d) None of these

44) The reaction between H2 and O2 in the presence of Pt to form water occurs with explosive violence but there is no reaction in the absence of a catalyst. This shows the
a) Activity of the catalyst
b) Selectivity of the catalyst
c) Promotion of a catalyst
d) None of these

45) Catalytic poisons act by
a) Preferential adsorption on the catalyst surface
b) Chemical combination with any one of the reactants
c) Increasing the rate of the backward reaction
d) Making the products chemically inactive

46) A substance like CO, As2O3, HCN etc., which paralyses the catalytic activity of a catalyst is called a/an
a) negative catalyst
b) Auto catalyst
c) promoter
d) Poison

47) Which of the following is an incorrect statement?
a) Adsorption decreases surface energy
b) Enzymes are highly specific in their reactions
c)
d) In a reversible reaction, a catalyst affects the forward reaction more than a backward reaction

48) As a general rule, adding a catalyst to a reacting system
a) Increases the yield of the product
b) Decreases the yield of the product
c) Does not affect the yield of product
d) Increases and decreases the yield irregularly

49) The effect of a catalyst in a reversible reaction is to
a) Reduce the energy of activation
b) Lower the rate of the backward reaction
c) Increase the heat of reaction
d) Alter the equilibrium composition

50) Which of the following statements is wrong?
a) The catalytic activity of enzymes is due to their capacity to lower the activation energy of a particular reaction
b) The catalytic activity of an enzyme is not specific
c) An enzyme reaction is highly sensitive to temperature
d) Enzymes are proteins in nature

51) In homogeneous catalytic reactions, the rate of reaction
a) Depends upon the concentration of the catalyst
b) Independent of the concentration of the catalyst
c) Depends upon the free energy change
d) Depends upon the physical state of the catalyst

52) In temporary poisoning, catalytic poisons act by
a) Coagulating the catalyst
b) Chemically combining with any one of the reactants
c) Chemically combining with the catalyst
d) Getting physically adsorbed on the active centers of the catalyst

53) A catalyst is used
a) Only for increasing the velocity of the reaction
b) For altering the velocity of the reaction
c) Only for decreasing the velocity of the reaction
d) All are correct

54) Which statement is more correct?
a) A catalyst only accelerates the rate of a chemical reaction
b) The catalyst cannot start a chemical reaction
c) The catalyst can retard the rate of chemical reaction
d) The catalyst cannot control the speed of a reaction

55) Which acts as a promoter for nickel in the hydrogenation of oils?
a) Cu
b) Mo
c) Fe
d) Pt

56) A chemical reaction is catalysed by X. Hence X
a) Does not affect the equilibrium constant of the reaction
b) Decreases the rate constant of the reaction
c) Reduces the enthalpy of the reaction
d) Increases the activation energy of the reaction

57) Which is true about a catalyst?
a) The catalyst altered during the reaction is regenerated
b) It does not alter the equilibrium
c) It lowers the energy of activation
d) All are true

58) Enzymes take part in reaction and
a) Decrease the rate of reaction
b) Increase the rate of reaction
c) Both (a) and (b)
d) None

59) V2O5 has replaced Pt as catalyst in the contact process because
a) It is cheap
b) It is not easily poisoned
c) Both are correct
d) None is correct

60) The destruction of the biological nature and activity of an enzyme by heat or chemical agent is called
a) Denaturation
b) Destruction
c) Dehydration
d) Killing

61) The modern theory of heterogeneous catalysis is
a) The intermediate compound formation theory.
b) the adsorption theory.
c) Both (a) and (b).
d) None.

62) When a catalyst increases the rate of a chemical reaction, the rate constant
a) Increases
b) Decreases
c) Remains constant
d) Becomes infinite

63) Which does not influence the rate of reaction?
a) Catalyst
b) Temperature
c) Concentration of reactants
d) All of these influence the rate of reaction

64) The dimensions for the rate of a reaction are
a) Moles lit -1

b) Moles lit Sec -1

c) Moles lit -1 Sec -1

d) Moles -2 lit -2 Sec -1

65) The rate of a certain reaction increases by 2.3 times when the temperature is raised from 300 K to 310 K. If k is the rate constant at 300 K then the rate constant at 310 K will be equal to
a) 2 k
b) k
c) 2. 3 k
d) (k) 23

66) The half life period for the catalytic decomposition of AB3 at 50 mm is found to be 4 hrs and at 100 mm it is 2.0 hrs. The order of the reaction is

a) 3
b) 1
c) 2
d) 0

67) The effect of temperature on the reaction rate is given by
a) Arrhenius equation
b) Gibbs Helmhotz equation
c) Kirchoff’s equation
d) None of the above

68) The catalytic decomposition of H2O2 is a reaction of
a) Zero order
b) First order
c) Second order
d) Third order

69) The temperature coefficient for most reactions lies between
a) 1 and 3
b) 2 and 3
c) 1 and 4
d) 2 and 4

70) A reaction is 75% complete in 32 minutes. The time taken for 50% of the reaction to be completed will be

a) 1.6 min
b) 160 min
c) 16 min
d) 61 min

71) The activation energy of a reaction is zero. The rate constant of the reaction
a) Increases with increase of temperature
b) Decreases with increase of temperature
c) Decreases with decrease of temperature
d) Is nearly independent of temperature

72) For the first order reaction with rate constant k the half life period (initial concentration = a) is equal to
a)
b)
c)
d)

73) For a reaction whose rate expression is rate = K [ A ] 1/2  [ B ] 3/2, the order of the reaction would be
a) 1
b) 3/2
c) 3/4
d) 2

74) The rate of the time required for 3/4th of a reaction of the first order to be completed to that required for half of the reaction is
a) 4 : 3
b) 3 : 2
c) 2 : 1
d) 1 : 2

75) If the time for the half change of a reaction is found to be inversely proportional to the square of the initial concentration, the order of the reaction is
a) 1
b) 2
c) 3
d) 4

76) A graph between time t and substance consumed at any time , i.e, x is found to be a straight line through the origin. This indicates that the reaction is of the
a) First order
b) Second order
c) Zero order
d) Third order

77) What is the direction of the reaction when one of the products of the reaction is removed from it?
a) Forward
b) Backward
c) The reaction stops
d) All are correct

78) The process which is catalysed by one of the products is known as
a) Auto catalysis
b) Anti catalysis
c) Negative catalysis
d) Acid catalysis


Answer :

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