chemical engineering chemical reaction MCQs – Page 5

Practise multiple-choice questions from chemical engineering chemical reaction for competitive examinations and subject revision. Review each marked answer and report any item that may be outdated or unclear.

chemical engineering chemical reaction Mcqs

81. According to the law of mass action, the rate of reaction is directly proportional to the__________________?
0

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 ?
0

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) ?
0

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 _______________________?
0

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_______________________?
0

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?
0

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 ?
0

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_________________?
0

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.) ?
0

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________________?
0

A. V.n

B. 1/V

C. V/n

D. V

96. The residence time distribution of an ideal CSTR is _____________________?
0

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?
0

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 _____________________?
0

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

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