Explore topic-wise MCQs in Chemical Engineering.

This section includes 1443 Mcqs, each offering curated multiple-choice questions to sharpen your Chemical Engineering knowledge and support exam preparation. Choose a topic below to get started.

851.

Collision theory gives the rate constant for bimolecular reaction as

A. K α T.e-E/RT
B. K α eE/RT
C. K α e-E/RT
D. none of these
Answer» D. none of these
Discussion
852.

The rate of reaction does not decrease appreciably as the reaction proceeds in case of __________ reactions.

A. autocatalytic
B. exothermic
C. endothermic
D. autothermal
Answer» B. exothermic
Discussion
853.

Arrhenious equation represents graphically the variation between the __________ and temperature.

A. rate of reaction
B. frequency factor
C. rate constant
D. activation energy
Answer» D. activation energy
Discussion
854.

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.

A. film diffusion
B. diffusion through ash layer
C. chemical reaction
D. either (a), (b) or (c)
Answer» C. chemical reaction
Discussion
855.

Sum of the powers of the concentration terms in the rate equation is called the __________ of the reaction.

A. order
B. overall order
C. molecularity
D. none of these
Answer» C. molecularity
Discussion
856.

In which of the following gaseous phase reactions, the equilibrium of the reaction remains unaffacted by pressure changes ?

A. 2O3 3O2
B. N2 + O2 2NO
C. 2NO2 N2O4
D. 2SO2 + O2 2SO3
Answer» C. 2NO2 N2O4
Discussion
857.

Which of the following factors control the design of a fluid-solid reactor ?

A. Reaction kinetics for single particle,
B. Size distribution of solids beingtreated.
C. Flow patterns of solids and fluid in the reactor.
D. All (a), (b) and (c).
Answer» E.
Discussion
858.

The following gas phase reactions are carried out isothermally in a CSTR.A 2R ; r1 = k1pA ;k1 = 20mole/(sec.m3 bar)A 3S ; r2 = k2 pA ;k2 = 40mole/(sec.m3 .bar)What is the maximum possible value of FR(mole/sec.) ?

A. 43525
B. 43497
C. 43526
D. 2
Answer» D. 2
Discussion
859.

The half life period of a first order reaction is

A. always the same irrespective of the reaction.
B. dependent on initial concentration of the reactants.
C. proportional to the initial concentration of reactants.
D. half the specific rate constant.
Answer» C. proportional to the initial concentration of reactants.
Discussion
860.

The half life period of a first order reaction is given by (where, K = rate constant. )

A. 1.5 K
B. 2.5 K
C. 0.693/K
D. 6.93 K
Answer» D. 6.93 K
Discussion
861.

__________ catalytic reaction is involved in the thermal cracking of gas oil.

A. Homogeneous
B. Homogeneous non
C. Heterogeneous
D. Heterogeneous non
Answer» B. Homogeneous non
Discussion
862.

The performance equations for constant density systems are identical for

A. P.F.R. and backmix reactor.
B. P.F.R. and batch reactor.
C. P.F.R, batch reactor and backmix reactor.
D. batch reactor and backmix reactor.
Answer» C. P.F.R, batch reactor and backmix reactor.
Discussion
863.

What is the order of a chemical reaction whose rate is deter-mined by the variation of one concentration term only ?

A. zero
B. first
C. second
D. third
Answer» C. second
Discussion
864.

With an increase in pressure in gaseous phase chemical reactions, the fractional conversion __________ when the number of moles decreases.

A. increases
B. decreases
C. remains unaffected
D. unpredictable from the data
Answer» B. decreases
Discussion
865.

Pure ethanol vapor is fed to a reactor packed with alumina catalyst, at the rate of 100 kmole / hr. The reactor products comprise: ethylene :95 kmole / hr, water vapour: 97.5 k mole / hr and diethyl ether :2.5 kmole/hr. The reactions occuring can be represented by:C2H5OH C2H4 + H2O2C2H5OH C2H5 - O - C2H5 + H2OThe percent conversion of ethanol in the reactor is

A. 100
B. 97.5
C. 95
D. 2.5
Answer» B. 97.5
Discussion
866.

What is the order of a chemical reaction in which doubling the initial concentration of the reactants doubles the half life time of the reaction ?

A. 0
B. 1
C. 2
D. 3
Answer» B. 1
Discussion
867.

An endothermic aqueous phase first order irreversible reaction is carried out in an adiabatic plug flow reactor. The rate of reaction

A. is maximum at the inlet of the reactor.
B. goes through a maximum along the length of the reactor.
C. goes through a minimum along the length of the reactor.
D. is maximum at the exit of the reactor.
Answer» B. goes through a maximum along the length of the reactor.
Discussion
868.

Fluid flow in a real packed bed can be approximated as __________ model.

A. plug flow
B. dispersion
C. mixed flow
D. tank in series
Answer» C. mixed flow
Discussion
869.

A pulse tracer is introduced in an ideal CSTR (with a mean residence time ι) at time, t = 0. The time taken for the exit concentration of the tracer to reach half of its initial value will be$

A. 2τ
B. 0.5τ
C. τ/0.693
D. 0.693τ
Answer» B. 0.5œÑ
Discussion
870.

Three plug flow reactors (PFR's) 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.

A. 100
B. 150
C. 200
D. 225
Answer» B. 150
Discussion
871.

For the liquid phase parallel reactions:R, rR = K1.CA2; E1 = 80 KJ/moleS, rs = K1.CA ; E2 = 120 KJ/mole The desired product is R. A higher selectivity of R will be achieved, if the reaction is conducted at

A. low temperature in a CSTR.
B. high temperature in a CSTR.
C. low temperature in a PFR.
D. high temperature in a PFR.
Answer» E.
Discussion
872.

In a reaction, the threshold energy is equal to (where, A = activation energy N = normal energy of reactants)

A. A
B. N
C. A+N
D. A-N
Answer» D. A-N
Discussion
873.

Fractional conversion __________ for an exothermic reversible chemical reaction, when the temperature is maximum.

A. increases
B. remains unchanged
C. decreases
D. unpredictable from the data
Answer» D. unpredictable from the data
Discussion
874.

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

A. 43526
B. 43682
C. 43525
D. 43680
Answer» C. 43525
Discussion
875.

In the fluid catalytic cracker (FCC), the cracking reaction is __________ (A) and the regeneration is___(B) __________

A. (A) exothermic (B) endothermic
B. (A) exothermic (B) exothermic
C. (A) endothermic (B) enodthermic
D. (A) endothermic (B) exothermic
Answer» E.
Discussion
876.

Decomposition rate of a liquid 'X' which decomposes as per the reaction is given by

A. K1 . CX
B. (K1 + K2 + K3)CX
C. (K1 + K2)CX
D. (K2 + K3)CX
Answer» D. (K2 + K3)CX
Discussion
877.

If the pore diffusion controls in a catalytic reaction, the apparent activation energy Ea is equal to

A. the intrinsic activation energy E.
B. (E + ED) where ED is activation due to diffusion.
C. (E + ED)/2
D. ED/2
Answer» E.
Discussion
878.

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

A. 1
B. 0.5
C. 0.1
D. 0
Answer» D. 0
Discussion
879.

The excess energy of the reactants required to dissociate into products is known as the __________ energy.

A. thermal
B. activation
C. threshold
D. binding
Answer» C. threshold
Discussion
880.

For the irreversible elementary first order reaction in parallel viz. , a plot of Cy Vs. Cz will give a straight line having a slope of

A. K2/K1
B. K1/K2
C. K1 . K2
D. K1 + K2
Answer» C. K1 . K2
Discussion
881.

A first order reaction requires two unequal sized CSTR. Which of the following gives higher yield ?

A. Large reactor followed by smaller one.
B. Smaller reactor followed by larger one.
C. Either of the arrangement (a) or (b) will give the same yield.
D. Data insufficient, can't be predicted.
Answer» D. Data insufficient, can't be predicted.
Discussion
882.

A spherical porous catalyst particle of radius R is subjected to reactant A which reacts to form B by a zero order surface reaction A B. Film mass transfer resistance is negligible and pore diffusion of A is rate controlling. The effectiveness factor of the catalyst is reported as 7/8. Which of the following statement is true?

A. Inner catalyst core of radius R/8 does not participate in reaction.
B. Inner catalyst core of radius R/2 does not participate in reaction.
C. Inner catalyst core of radius 7R/8 does not participate in reaction.
D. Effectiveness factor for a zero order reaction can not be 7/8 as it must always be 1.
Answer» B. Inner catalyst core of radius R/2 does not participate in reaction.
Discussion
883.

For the chemical reaction P Q, it is found that the rate of reaction doubles as the concentration of 'P' is doubled. If the reaction rate is proportional to Cpn, then what is the value of 'n' for this chemical reaction ?

A. 1
B. 2
C. 3
D. 0
Answer» B. 2
Discussion
884.

The conversion in a mixed reactor/accomplishing a reaction A 3R is 50% when gaseous reactant 'A' is introduced at the rate of 1 litre/second and the leaving flow rate is 2 litres/second. The holding time for this operation is __________ second.

A. 0.5
B. 1
C. 2
D. 3
Answer» B. 1
Discussion
885.

In chamber process of sulphuric acid manufacture in industry, the gas phase oxidation of SO2 to SO3 is accomplished by a __________ reaction.

A. non-catalytic homogeneous
B. non-catalytic heterogeneous
C. catalytic homogenous
D. catalytic heterogeneous
Answer» D. catalytic heterogeneous
Discussion
886.

For a packed bed reactor; the presence of a long tail in the residence time distribution curve is an indication of

A. ideal plug flow
B. bypass
C. dead zone
D. chanelling
Answer» D. chanelling
Discussion
887.

The conversion of a reactant, undergoing a first order reaction, at a time equal to three times the half life of the reaction is

A. 0.875
B. 0.5
C. 0.425
D. data insufficient to calculate
Answer» B. 0.5
Discussion
888.

In the gaseous phase ammonia formation reaction (N2 + 3H2 2NH3), the value of the equilibrium constant depends on the

A. total pressure of the system.
B. volume of the reactor.
C. temperature.
D. initial concentration of N2 and H2.
Answer» D. initial concentration of N2 and H2.
Discussion
889.

In case of a/an __________ chemical reaction, conversion increases with the rise in temperature.

A. reversible exothermic
B. irreversible exothermic
C. irreversible endothermic
D. reversible endothermic
Answer» E.
Discussion
890.

Which of the following will favour the reverse reaction in a chemical equilibrium reaction ?

A. Increasing the concentration of one of the reactants.
B. Increasing the concentration of one or more of the products.
C. Removal of at least one of the products at regular interval.
D. None of these.
Answer» C. Removal of at least one of the products at regular interval.
Discussion
891.

The energy of activation of a chemical reaction

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).
Answer» C. varies as fifth power of the temperature.
Discussion
892.

Effectiveness factor (E) of a catalyst pellet is defined as, Effectiveness factor for a first order reaction is given by (where, T = Thiele modulus)

A. tan hT/T
B. tan T/T
C. tan hT/tan T
D. none of these
Answer» B. tan T/T
Discussion
893.

Which of the following is the optimum operating condition for an exothermic reversible reaction taking place in a plug-flow reactor ?

A. Temperature should be high in the beginning and decreased towards the end of the reaction.
B. Very low temperature should be used throughout the reaction.
C. Very high temperature should be used throughout the reaction.
D. none of these.
Answer» B. Very low temperature should be used throughout the reaction.
Discussion
894.

From Arhenius law, a plot of loge K versus 1/T gives a straight line with a slope of (-E/R). The unit of E/R is

A. k cal
B. k cal/°K
C. °K
D. k cal. °K
Answer» D. k cal. ¬∞K
Discussion
895.

A catalyst in a chemical reaction __________ free energy change in the reaction.

A. increases
B. decreases
C. either (a) or (b); depends on the type of catalyst
D. neither (a) nor (b).
Answer» D. neither (a) nor (b).
Discussion
896.

Space time equals the mean residence time

A. when the density of the reaction mixture is constant.
B. for large diameter tubular reactor.
C. for narrow diameter tubular reactor.
D. for CSTR.
Answer» B. for large diameter tubular reactor.
Discussion
897.

With increase in temperature, the equilibrium __________ rises in case of endothermic reaction.

A. constant
B. conversion
C. both (a) & (b)
D. neither (a) nor (b)
Answer» C. both (a) & (b)
Discussion
898.

A pollutant P degrades according to first order kinetics. An aqueous stream containing P at 2 kmole/m3 and volumetric flow rate 1m3 /h requires a mixed flow reactor of volume V to bring down the pollutant level to 0.5 kmole/m3 . The inlet concentration of the pollutant is now doubled and the volumetric flow rate is tripled. If the pollutant level is to be brought down to the same level of 0.5 kmole/m3 , the volume of the mixed flow reactor should be increased by a factor of

A. 7
B. 6
C. 3
D. 43531
Answer» B. 6
Discussion
899.

For the non catalytic reaction of particles with surrounding fluid, the same needed to achive the same fractional conversion for particles of different unchanging sizes is proportional to the particle diameter, when the __________ is the controlling resistance.

A. film diffusion
B. diffusion through ash layer
C. chemical reaction
D. either (a), (b) or (c)
Answer» D. either (a), (b) or (c)
Discussion
900.

In autocatalytic reactions,

A. one of the reactants acts as a catalyst.
B. one of the products acts as a catalyst.
C. catalysts have very high selectivity.
D. no catalyst is used.
Answer» C. catalysts have very high selectivity.
Discussion