chemical engineering chemical reaction Mcqs
51. Kinetics of a solid catalysed reaction can best be studied in a _________________ reactor?
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A. Batch

B. None of these

C. Mixed

D. Plug-flow

52. For the irreversible elementary reactions in parallel as shown in the bellow figure, the rate of disappearance of X is equal to_______________?
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A. CA . K1/2

B. CA (K1 + K2)/2

C. CA . K2/2

D. CA (K1 + K2)
53. In chamber process of sulphuric acid manufacture in industry, the gas phase oxidation of SO2 to SO3 is accomplished by a ______________ reaction ?
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A. Catalytic homogenous

B. Non-catalytic heterogeneous

C. Catalytic heterogeneous

D. Non-catalytic homogeneous

54. The conversion XA and residence time data are collected for zero order liquid phase reaction in a stirred tank reactor. Which of the following will be a straight line ?
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A. XA/(1 XA)Vs ?

B. XA Vs ln ?

C. XA(1 XA)Vs ?

D. XA Vs . ?
55. In a semi-batch reactor _____________________?
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A. Velocity of reaction can be controlled

B. Maximum conversion can be controlled

C. Both the reactants flow counter-currently

D. Residence time is constant

56. Maximum equilibrium conversion for endothermic reaction is obtained at the ______________ temperature?
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A. Highest possible

B. Lowest possible

C. Intermediate

D. Room

57. Following isothermal kinetic data are obtained in a basket type of mixed flow reactor for a porous catalyst. Determine the role of pore diffusion and external mass transfer processes ?
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A. Strong pore diffusion control and mass transfer not controlling

B. Both pore diffusion and mass transfer not controlling

C. Both pore diffusion and mass transfer controlling

D. Mass transfer controlling

58. For any reaction, we may write conversion as a function of______________________?
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A. Concentration

B. Time

C. Temperature

D. All A., B. & C.
59. For the reaction as shown in the bellow figure, the rate of formation of Z is 0.2 gm mole/litre.hr. What is the rate of disappearance of X in gm mole/litre.hr ?
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A. 0.1

B. 0.4

C. 0.2

D. None of these

60. Which of the following holds good for an elementary reaction as shown in the bellow figure ?
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A. The rate of disappearance of Y is equal to the rate of disappearance of X

B. The rate of disappearance of X is equal to the rate of appearance of Z

C. The rate of disappearance of Y is equal to the rate of appearance of Z

D. Three times the rate of disappearance of X is equal to the rate of appearance of Z
61. What is the order of a chemical reaction of the bellow figure, if the rate of formation of C, increases by a factor of 2.82 on doubling the concentration of A and increases by a factor of 9 on trebling the concentration of B ?
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A. 7/2

B. 4-May

C. 4-Jul

D. 2-May

62. Promoter_____________________?
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A. ating discontinuities in the crystals</strong>

B. Increases the number of active centres by increasing the unevenness of catalyst surface and by

C. Alters the position of equilibrium in a reversible reaction

D. All A., B. and C.

E. Initiates a chemical reaction and is a catalyst by itself

63. A chemical reaction, A ? 3B, is conducted in a constant pressure vessel. Starting with pure A, the volume of the reaction mixture increases 3 times in 6 minutes. The fractional conversion is ___________________?
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A. Data insufficient, cant be predicted

B. 1

C. 0.33

D. 0.5

64. The reactions with low activation energy are _____________________?
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A. Slow

B. Fast

C. Always spontaneous

D. Non-spontaneous

65. The rate at which a chemical substance reacts is proportional to its____________________?
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A. Equivalent weight

B. Molecular weight

C. Active mass

D. None of these

66. BET apparatus is used to determine the ___________________?
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A. Pore diameter

B. Specific surface of a porous catalyst

C. Pore size distribution

D. Porosity of the catalyst bed

67. A stirred tank reactor compared to tubular-flow reactor provides____________________?
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A. Higher overall selectivity for a first order consecutive reaction

B. More uniform operating conditions

C. All A., B. and C.

D. Permits operation at the optimum temperature for a long reaction time

68. The order of a chemical reaction is__________________?
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A. Always equal to the total stoichiometric number of reactants

B. Never fractional

C. None of these

D. An experimentally determined quantity
69. For a heterogeneous catalytic reaction, A + B ? C, with equimole feed of A and B, the initial rate rA0 is invariant with total pressure. The rate controlling step is______________________?
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A. Desorption of C

B. Surface reaction between absorbed A and absorbed B

C. Surface reaction between A in the gas phase and absorbed B

D. Surface Kc/(1 + TS) reaction between absorbed A and B in the gas phase

70. Three plug flow reactors (PFRs) of 4, 5 & 6 m3 volumes are arranged in two branches as shown below in the figure. If the total feed rate is 300 tons/hr, then for the same conversion in each branch, the feed rate through branch II should be ______________ tons/hr ?
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A. 100

B. 150

C. 225

D. 200

71. Cold shot cooling is only practical when the feed temperature is ______________ than the reaction temperature?
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A. Higher

B. Lower

C. Much higher

D. Much lower
72. Which of the following is not endothermic in nature ?
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A. Steam reforming of naphtha

B. Gasification of carbon

C. Thermal cracking of fuel oil

D. Combustion of sulphur
73. The exit age distribution of a fluid leaving a vessel (denoted by E) is used to study the extent of non-ideal flow in the vessel. The value of ?? 0 E.dt is____________________?
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A. ?

B. 0

C. 1

D. ?2?

74. A reaction which is catalysed by an acid is also catalysed by any substance, which has a tendency to _________________?
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A. Lose a proton

B. None of these

C. Lose an electron

D. Gain a proton

75. Time required for 50% decomposition of a liquid in an isothermal batch reactor following first order kinetics is 2 minutes. The time required for 75% decomposition will be about _______________ minutes?
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A. 10

B. 6

C. 4

D. 3

76. With the same reaction time, initial concentration and feed rate, the reaction 2A ? B is carried out separately in CSTR and P.F. reactor of equal volumes. The conversion will be__________________?
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A. Higher in P.F. reactor

B. Higher in CSTR

C. Same in both the reactors

D. Data insufficient; cant be predicted

77. Calcination reaction of limestone (CaCO3 ? CaO + CO2) goes to completion in the rotary kiln, because____________________?
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A. Of high calcination temperature

B. CO2 escapes continuously

C. CaO is more stable than CaCO3

D. CaO is not dissociated

78. In case of a P.F.R., there__________________________?
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A. May be lateral mixing of fluid

B. Should not be any mixing along the flow path

C. Both A. and B.

D. Neither A. nor B.

79. For every 10C rise in temperature, the rate of chemical reaction doubles. When the temperature is increased from 30 to 70C, the rate of reaction increases ______________ times?
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A. 12

B. 8

C. 16

D. 32

80. For a zero order reaction, the concentration of product increases with the _____________________?
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A. Increase of reaction time

B. Increase in initial concentration

C. Total pressure

D. Decrease in total pressure

81. According to the law of mass action, the rate of reaction is directly proportional to the__________________?
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A. Volume of the reaction vessel

B. Equilibrium constant

C. Molar concentration of the reactants

D. Nature of the reactants

82. 6 gm of carbon is burnt with an amount of air containing 18 gm oxygen. The product contains 16.5 gms CO2 and 2.8 gms CO besides other constituents. What is the degree of conversion on the basis of disappearance of limiting reactant ?
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A. 100%

B. 95%

C. 75%

D. 20%

83. A chemical reaction is of zero order, when the reaction rate is (where, CA = concentration of reactant) ?
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A. ? 1/CA

B. None of these

C. Independent of temperature

D. ? CA

84. Space time in flow reactor is____________________?
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A. Usually equal to the residence time

B. The reciprocal of the space velocity

C. A measure of its capacity

D. Both A. and B.
85. The gas phase reaction 2A ? B is carried out in an isothermal plug flow reactor. The feed consists of 80 mole % A and 20 mole % inerts. If the conversion of A at the reactor exit is 50%, then CA/CA0 at the outlet of the reactor is _______________________?
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A. 5/8

B. 8-Mar

C. 3-Feb

D. 3-Jan

86. For a tubular flow reactor with uniform concentration and temperature, the independent variable is___________________?
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A. Time

B. Diameter

C. None of these

D. Length
87. In the hydrodealkylation of toluene to benzene, the following reactions occur: C7H8 + H2 ? C6H6 + CH4 2C6H6 ? C12H10 + H2 Toluene and hydrogen are fed to a reactor in a molar ratio 1:5.80% of the toluene gets converted and the selectivity of benzene(defined as moles of benzene formed/moles of toluene converted) is 90%. The fractional conversion of hydrogen is_______________________?
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A. 0.144

B. 0.152

C. 0.136

D. 0.16

88. An example of autothermal reactor operation is______________________?
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A. Ammonia synthesis

B. Ethylene oxidation

C. Sulphur dioxide oxidation

D. Benzene oxidation

89. A chemical reaction occurs when the energy of the reacting molecules is __________________ the activation energy of the reaction?
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A. Less than

B. Equal to

C. More than

D. Equal to or more than
90. The rate of the chemical reaction A ? B doubles as the concentration of A i.e.., CA is doubled. If rate of reaction is proportional to CA n, then what is the value of n for this reaction ?
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A. 1

B. 0.5

C. 2

D. 0

91. For a homogeneous reaction of nth order, the dimension of the rate constant is given by_________________?
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A. None of these

B. 1/(time)n

C. (Concentration)n 1/(time)

D. (Concentration)1 n/(time)
92. Which of the following is not a dimension-less group used in catalysis? (Where, D = dispersion co-efficient, cm2/sec.D1 = diffusion co-efficient; cm2/sec L = length of the reactor, cm t = time, sec, v = volumetric flow rate, cm3/sec. V = volume, cm3.) ?
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A. Thiele modulus L ?(k/D1)

B. Reactor dispersion number (D/vL)

C. None of these

D. Reduced time (vt/V)

93. A first order reaction requires two equal sized CSTR. The conversion is____________________?
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A. More when they are connected in parallel

B. More when they are connected in series

C. Less when they are connected in series

D. Same whether they are connected in series or in parallel

94. The energy of activation of a chemical reaction ?
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A. Is same as heat of reaction at constant pressure

B. Is the minimum energy which the molecules must have before the reaction can take place

C. Varies as fifth power of the temperature

D. Both B. and C.

95. n number of plug flow reactors (P.F.R) in series with a total volume V gives the same conversion as one P.F.R. of volume________________?
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A. V.n

B. 1/V

C. V/n

D. V
96. The residence time distribution of an ideal CSTR is _____________________?
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A. (1/?) exp (-t/?)

B. ? exp (-t/?)

C. (1/?) (-t/?)

D. exp (-t/?)
97. The equilibrium constant of a catalytic chemical reaction _______________ due to the presence of?
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A. atalyst.

B. Decreases

C. Remain unaffected

D. Increases

E. Unpredictable from the data

98. The extent of a reaction is ___________________?
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A. Different for reactants and products

B. All of the above

C. Depends on the stoichiometric co-efficient

D. Dimensionless

99. Which of the following resistances is not involved in a gas phase catalytic (gas-solid) reaction ?
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A. Ash resistance

B. Gas film and pore surface diffusion resistances for products

C. Surface phenomenon resistance

D. Gas film and pore surface diffusion resistances for reactants

100. The irreversible reaction, X ? Y, is the special case of the reversible reaction, X ? Y, in which the _____________________?
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A. All A., B. and C.

B. Equilibrium constant is infinite

C. Concentration of A at equilibrium is zero

D. Fractional conversion of A at equilibrium is unity