chemical engineering Mcqs
2901. The catalyst in a first order chemical reaction changes the_________________?
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A. Heat of reaction

B. Heat of formation of the product

C. Activation energy

D. Equilibrium constant

2902. For series reaction, the relative yield__________________?
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A. Is always greater for plug-flow reactor than for the single CSTR of the same volume

B. Statement in A. is wrong

C. Decreases with increasing conversion

D. Both A. and C. hold good
2903. The exit age distribution of fluid leaving a vessel is used to know the__________________?
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A. Activation energies of a reaction

B. None of these

C. Extent of non-ideal flow in the vessel

D. Reaction mechanism

2904. Which of the following is the optimum operating condition for an exothermic reversible reaction taking place in a plug-flow reactor ?
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A. Very low temperature should be used throughout the reaction

B. Very high temperature should be used throughout the reaction

C. None of these

D. Temperature should be high in the beginning and decreased towards the end of the reaction
2905. 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

2906. The equilibrium constant K of a chemical reaction depends on_________________?
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A. Ratio of reactants

B. Temperature only

C. Pressure only

D. Temperature and pressure

2907. In a continuous flow stirred tank reactor, the composition of the exit stream_________________?
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A. Is same as that in the reactor

B. Depends upon the flow rate of inlet stream

C. Is different than that in the reactor

D. None of these

2908. A space time of 3 hours for a flow reactor means that___________________?
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A. ours</strong>

B. Conversion is cent per cent after three hours

C. It takes three hours to dump the entire volume of the reactor with feed

D. Three reactor volumes of feed can be processed every hour

E. The time required to process one reactor volume of feed (measured at specified conditions) is
2909. For identical flow rate and feed composition, X plug flow reactors (PER) in series with a total volume V gives the same conversion as single_______________?
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A. PFR of volume V/X

B. CSTR of volume V/X

C. PFR of volume V

D. CSTR of volume V

2910. Unreacted core model represents the reaction involving ______________________?
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A. None of these

B. Roasting of sulphide ores

C. Combustion of coal particles

D. Manufacture of carbon disulphide from elements

2911. 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. 0.16

B. 0.152

C. 0.144

D. 0.136

2912. The rate constant of a reaction is a function of the ___________________?
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A. Initial concentration of the reactants

B. Temperature of the system

C. Time of reaction

D. Extent of reaction

2913. In which of the following gaseous phase reactions, the equilibrium of the reaction remains unaffected by pressure changes ?
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A. 2SO2 + O2 ? 2SO3

B. 2NO2 ? N2O4

C. N2 + O2 ? 2NO

D. 2O3 ? 3O2

2914. Chemical kinetics can predict the _______________ of a chemical reaction?
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A. Rate

B. Feasibility

C. Both A. & B.

D. Neither A. nor B.

2915. A reaction which is catalysed by a base is catalysed by all substances which have a tendency to_______________________?
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A. None of these

B. Gain an electron

C. Gain a proton

D. Lose a proton

2916. The reaction between oxygen and organic material is a/an _____________ reaction?
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A. Photochemical

B. Exothermic

C. Biochemical

D. Endothermic

2917. The first order gas phase reaction as shown in the bellow figure is conducted isothermally in batch mode. The rate of change of conversion with time is given by________________?
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A. dXA/dt = k1 (1 XA)/(1 + XA)

B. dXA/dt = k1 (1 XA) (1 + 0.5XA)

C. dXA/dt = k1 (1 XA)

D. dXA/dt = k1 (1 XA)2 (1 + 2XA)

2918. The effectiveness factor for large value of Thiele modulus [L?(K/D1)] of a solid catalysed first order reaction is equal to (where, L = length of the reactor, cm, D1 = diffusion co-efficient, cm2/second) ?
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A. ?

B. L ?(K/D1)

C. 1/[L?(K/D1)]

D. 1

2919. Differential method for analysing the kinetic data is used ___________________?
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A. When rate expressions are very simple

B. For testing complicated mechanisms

C. None of these

D. When the data are scattered

2920. In autocatalytic reactions ?
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A. No catalyst is used

B. One of the products acts as a catalyst

C. Catalysts have very high selectivity

D. One of the reactants acts as a catalyst

2921. A back mix reactor is___________________?
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A. Ideal at very low conversion

B. Same as plug flow reactor (PFR)

C. Suitable for gas phase reactions

D. Same as ideal stirred tank reactor
2922. For the non-catalytic reaction of particles with surrounding fluid, the time needed to achieve the same fractional conversion for particles of different but unchanging sizes is proportional to the square of particle diameter, when the _______________ is the controlling resistance?
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A. Either A., B. or C.

B. Chemical reaction

C. Film diffusion

D. Diffusion through ash layer
2923. Knudsen diffusion is directly proportional to _____________________?
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A. ?T

B. T2

C. T

D. 1/?T

2924. For a first order chemical reaction in a porous catalyst, the Thiele modulus is 10. The effectiveness factor is approximately equal to ____________________?
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A. 0.1

B. 0

C. 0.5

D. 1

2925. For multiple reactions, the flow pattern within the vessel affects the ____________________?
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A. Size requirement

B. Distribution of reaction products

C. Both A. and B.

D. Neither A. nor B.

2926. 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

2927. Half life period of a first order irreversible reaction A ? B is ______________________?
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A. ln 0.5/k

B. k/2

C. ln 2/k

D. ln k/2

2928. For the reaction, A + B ? 2B + C,___________________?
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A. rA = -rB

B. rA = rB

C. rA = rB/2

D. rA = 2rB

2929. Helium-mercury method can be used to determine the _____________ of the catalyst particle?
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A. Porosity

B. All A., B., & C.

C. Pore volume

D. Solid density

2930. Decomposition rate of a liquid X which decomposes as per the reaction as shown in the bellow figure is given by________________?
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A. K1 . CX

B. (K2 + K3) CX

C. (K1 + K2 + K3) CX

D. (K1 + K2) CX
2931. The rate constant of a reaction depends on the __________________?
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A. Time of reaction

B. Initial concentration of reactants

C. Temperature of the system

D. Extent of reaction

2932. The equilibrium constant of a catalytic chemical reaction _______________ due to the presence of?
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A. Remain unaffected

B. Decreases

C. Unpredictable from the data

D. Increases

E. atalyst.

2933. As the chemical reaction proceeds, the rate of reaction ___________________?
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A. Increases

B. May increase or decrease depending on the type of reaction

C. Decreases

D. Remain same

2934. The rate constant of a chemical reaction increases by 100 times when the temperature is increased from 400 K to 500 K. Assuming transition state theory is valid, the value of E/R is __________________?
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A. 8987K

B. 9210K

C. 8621K

D. 8764K

2935. For the reversible reaction A ? 2B, if the equilibrium constant K is 0.05 mole/litre; starting from initially 2 moles of A and zero moles of B, how many moles will be formed at equilibrium ?
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A. 0.637

B. 0.253

C. 0.338

D. 0.152

2936. A second order reaction of the form A + B ? C is called a pseudo-first order reaction, when____________________?
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A. CA0 = CB0

B. CA0 > CB0

C. CB0 > CA0

D. CB0 ? CB0
2937. The rate constant of a chemical reaction increases by increasing the______________________?
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A. Pressure

B. Temperature

C. Reactants concentration

D. None of these

2938. The rate of a gas phase reaction is given by K . CA . CB. If the volume of the reaction vessel is reduced to l/4th of its initial volume, then the reaction rate compared to the original rate will be _______________ times?
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A. 4

B. 2

C. 16

D. 8

2939. 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.
2940. ______________ catalytic reaction is involved in the thermal cracking of gas oil ?
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A. Non-Homogeneous

B. Non-Heterogeneous

C. Homogeneous

D. Heterogeneous

2941. Reaction rate of a first order reaction, which is half completed in 23 minutes will be _________________?
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A. 0.03 sec-1

B. 0.03 hr-1

C. 0.03 min-1

D. 0.05 min-1

2942. The rate of the reaction, X ? Y, quadruples when the concentration of X is doubled. The rate expression for the reaction is, r = K Cx n, the value of n in this case will be_______________________?
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A. 3

B. 2

C. 0

D. 1

2943. 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. 200

D. 225

2944. Half life period of a chemical reaction is proportional to CA0 -1, if the reaction is of _______________ order?
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A. Zero

B. First

C. Second

D. Third

2945. If ?G (free energy change) for a chemical reaction is very large and negative, then the reaction is_______________________?
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A. Unpredictable as ?G is no measure of feasibility of a reaction

B. Very much feasible

C. Not feasible

D. Just feasible

2946. 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. 95%

B. 20%

C. 75%

D. 100%

2947. The rate expression for a heterogeneous catalytic reaction is given by, rA = K.KA PA(1 + KA.PA + KR.PR), where K is surface reaction rate constant and KA and KR are absorption equilibrium constants of A and R respectively. If KR PR >> (1 + KA PA), the apparent activation energy EA is equal to (given E is the activation energy for the reaction and ?HR and ?HA are the activation energies of adsorption of R and A) ?
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A. E

B. E + ?HA

C. ?HA + ?HR

D. E + ?HA ?HR)
2948. Which of the following is not endothermic in nature ?
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A. Gasification of carbon

B. Combustion of sulphur

C. Thermal cracking of fuel oil

D. Steam reforming of naphtha

2949. Overall rate of reaction in a heterogeneous catalytic reaction depends upon the mass and energy transfer from the fluid to solid surface and its rate of reaction is usually ________________ the concentration of catalyst, if it does not entail a chain mechanism?
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A. Independent of

B. Proportional to the square of

C. Inversely proportional to

D. Proportional to
2950. Integral method for analysing the kinetic data is used _____________________?
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A. When the data are scattered

B. For testing specific mechanisms with simple rate expressions

C. Both A. and B.

D. None of these