Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 1

A catalyst in a chemical reaction:


Options are :

  • Increases the frequency of collisions of reacting species
  • Decreases the activation energy
  • All of these
  • Alters the reaction mechanism

Answer :All of these

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 10

Design of heterogeous catalytic reactor involves consideration of __________ steps


Options are :

  • None of these
  • Only physical
  • Only chemical

Answer :Only physical Only chemical

Considering the endotheomic dissociation of CaCO3 in a closed vessel (CaCO3

CaO + CO2), the pressure of CO2 increases, if:


Options are :

  • None of these
  • A catalyst is added
  • The temperature is increased
  • An inert gas is pumped keeping the temperature constant

Answer :The temperature is increased

Half life period of a first order irreversible reaction A

B is:


Options are :

  • ln 2/k
  • ln 0.5/k
  • k/2
  • ln k/2

Answer :ln 2/k

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 11

The catalyst in a first order chemical reaction changes the:


Options are :

  • Heat of reaction
  • Heat of formation of the product
  • Activation energy
  • Equilibrium constant

Answer :Activation energy

When the reaction is dominated by in-traparticle diffusion, the apparent order of reaction (nD) as measured is related to the true order (n) as:


A.


B.



C.

nD = n + 1


D.

None of these


Options are :

  • B
  • D
  • C
  • A

Answer :A

The space time is equivalent to the holding time in a steady state mixed reactor for:


Options are :

  • Gas reactions with changing no. of moles
  • Constant fluid density systems
  • Non-isothermal gas reaction
  • Variable fluid density systems

Answer :Constant fluid density systems

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 2

For a tubular flow reactor with uniform concentration and temperature, the independent variable is:


Options are :

  • Time
  • Length
  • None of these
  • Diameter

Answer :Length

The performance equations for constant density systems are identical for:


Options are :

  • P.F.R. batch reactor and backmix reactor
  • P.F.R. and backmix reactor
  • Batch reactor and backmix reactor
  • P.F.R. and batch reactor

Answer :P.F.R. and batch reactor

In case of a consecutive unimolecular type first order reaction

, the concentration of component __________ increases continuously with time


Options are :

  • S
  • A
  • R
  • None of these

Answer :S

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 3

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:


Options are :

  • K1 + K2
  • K1/K2
  • K2/K1
  • K1 . K2

Answer :K1/K2

For the reaction

, 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 ?


Options are :

  • 0.2
  • 0.4
  • None of these
  • 0.1

Answer :0.4

The rate of forward reaction, at chemical equilibrium is____the rate of backward reaction:


Options are :

  • Equal to
  • Less than
  • Either B or C
  • More than

Answer :Equal to

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 4

The rate of a homogeneous reaction is a function of:


Options are :

  • All temperature, pressure and composition
  • Temperature and composition only
  • Temperature and pressure only
  • Pressure and composition only

Answer :All temperature, pressure and composition

An irreversible first order reaction is being carried out in a CSTR and PFR of same volume. The liquid flow rates are same. The relative conversion will:


Options are :

  • Depend on the temperature
  • Be same in both cases
  • Be more in PFR than in CSTR
  • Be more in CSTR than in PFR

Answer :Be more in PFR than in CSTR

Calcination reaction of limestone (CaCO3

CaO + CO2) goes to completion in the rotary kiln, because:


Options are :

  • CaO is not dissociated
  • CaO is more stable than CaCO3
  • of high calcination temperature
  • CO2 escapes continuously

Answer :CO2 escapes continuously

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 5

For a fluidised bed reactor, the most suitable/relevant model is a __________ model


Options are :

  • Bubbling bed
  • Tank in series
  • Plug flow
  • None of these

Answer :Bubbling bed

When a catalyst increases the rate of chemical reaction, the rate constant:


Options are :

  • Decreases
  • Becomes infinite
  • Remains constant
  • Increases

Answer :Increases

What is the unit of the rate constant in a chemical reaction in which 10% of the reactant decomposes in one hour, 20% in two hours, 30% in three hours and so on ?


Options are :

  • Litre/mole.second
  • Litre/mole
  • Litre/second
  • Moles/litre.second

Answer :Litre/mole.second

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 6

Volume change for unimolecular type first order reaction

, increases __________ with time


Options are :

  • Linearly
  • Parabolically
  • Logarithmically
  • Exponentially

Answer :Exponentially

The exit age distribution of fluid leaving a vessel is used to know the:


Options are :

  • Extent of non-ideal flow in the vessel
  • None of these
  • Activation energies of a reaction
  • Reaction mechanism

Answer :Extent of non-ideal flow in the vessel

According to Arhenious equation of temperature dependency of rate constant for an elementary reaction:


Options are :

  • None of these
  • k ? ?T
  • k ? e^(-E/RT)
  • k ? T e^(-E/RT)

Answer :k ? e^(-E/RT)

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 7

Slurry reactors are characterised by the:


Options are :

  • Presence of two mobile phases
  • None of these
  • Lack of intraparticle diffusion resistance

Answer :Presence of two mobile phases Lack of intraparticle diffusion resistance

An irreversible aqueous phase reaction, A + B

P, is carried out in an adiabatic mixed flow reactor. A feed containing 4kmole/m3 of each A and B enters the reactor at 8m3 /hr. If the temperature of the exit stream is never to exceed 390 K, what is the maximum inlet feed temperature allowed ?

Data: Heat of reaction = - 50 kJ/mole

Density of the reacting mixture = 1000kg/m3

Specific heat of reacting mixture = 2kJ/kg.K


The above data can be assumed to be independent of temperature and composition:


Options are :

  • 190
  • 290
  • 390
  • 490

Answer :290

The vessel dispersion number (D/?L) for plug flow is:


Options are :

  • 0
  • 500
  • 750
  • ?

Answer :0

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 8

Molecularity of a reaction:


Options are :

  • May not be equal to the order of reaction
  • Can't have a fractional value
  • None of these
  • Is always equal to the overall order of reaction

Answer :May not be equal to the order of reaction Can't have a fractional value

Half life period of decomposition of a liquid 'A' by irreversible first order reaction is 12 minutes. The time required for 75% conversion of 'A' is __________ minutes


Options are :

  • 12
  • 6
  • 18
  • 24

Answer :24

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:


Options are :

  • �K
  • k cal. �K
  • k cal/�K
  • k cal

Answer :�K

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 9

Chemical kinetics can predict the __________ of a chemical reaction:


Options are :

  • Both A and B
  • Neither A nor B
  • Rate
  • Feasibility

Answer :Rate

In case of calcination of limestone, CaCO3 CaO + CO2, the addition of more of CaO will result in __________ in the concentration of CO2


Options are :

  • Unpredictable from the data
  • Decrease
  • No change
  • Increase

Answer :No change

An exothermic reaction takes place in an adiabatic reactor. The product temperature __________ reactor feed temperature


Options are :

  • Is always less than
  • Is always equal to
  • May be greater or less than
  • Is always greater than

Answer :Is always greater than

During manufacture of H2SO4, the oxidation of SO2 to SO3 by oxygen is an en-dothermic reaction. The yield of SO3 will be maximised, if the:


Options are :

  • Temperature is reduced and pressure is increased
  • Pressure is reduced
  • Temperature is increased
  • Temperature is increased and pressure is reduced

Answer :Temperature is reduced and pressure is increased

Pick out the wrong statement:


Options are :

  • Reaction rate does not decrease appreciably as the reaction proceeds in case of an autocatalytic reaction
  • For an ideal mixed reactor at steady state, the exit stream has the same composition as fluid within the reactor and the space time is equivalent to holding time for constant density system
  • Plug flow reactor (PFR) is always smaller than mixed reactor for all positive reaction orders for a particular duty
  • For a first order consecutive reaction, a tubular flow reactor as compared to a stirred tank reactor provides higher overall selectivity

Answer :For a first order consecutive reaction, a tubular flow reactor as compared to a stirred tank reactor provides higher overall selectivity

An elementary liquid phase decomposition reaction

is to be carried out in a CSTR. The design equation is:


A.

k? = XA/(1 - XA)


B.

k? = XA(1 + XA)/(1 + XA)


C.

k? = XA/(1 - XA)2


D.


Options are :

  • B
  • C
  • D
  • A

Answer :A

Pick out the wrong statement:


Options are :

  • Autocatalytic reactions are exemplified by microbial fermentation reactions
  • The slowest step has the greatest influence on the overall reaction rate in case of an irreversible series reaction
  • The fractional conversion at any time is same for both the constant as well as the variable volume system in case of an irreversible unimolecular type first order reaction
  • Hydrolysis of ester in presence of alkali or acid is a zero order reaction

Answer :Hydrolysis of ester in presence of alkali or acid is a zero order reaction

The point selectivity of the product 'Y' in the reaction,



is equal to:


Options are :

  • K2/K1
  • K1/K2
  • K2-K1
  • K1-K2

Answer :K1/K2

An isothermal aqueous phase reversible reaction, P

R, is to be carried out in a mixed flow reactor. The reaction rate in k.mole/m3 .h is given by, r = 0.5CP - 0.125CR. A stream containing only P enters the reactor

The residence time required (in hours) for 40% conversion of P is:


Options are :

  • 1.33
  • 0.80
  • 2.67
  • 1.60

Answer :1.60

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


Options are :

  • Temperature should be high in the beginning and decreased towards the end of the reaction
  • Very low temperature should be used throughout the reaction
  • Very high temperature should be used throughout the reaction
  • None of these

Answer :Temperature should be high in the beginning and decreased towards the end of the reaction

Promoter is added to the catalyst to improve its:


Options are :

  • Porosity
  • Sensitivity
  • None of these
  • Surface area

Answer :Sensitivity

The first order gas phase reaction

is conducted isothermally in batch mode. The rate of change of conversion with time is given by:


A.


B.


C.


D.


Options are :

  • A
  • D
  • B
  • C

Answer :C

In case of a P.F.R., there:


Options are :

  • Should not be any mixing along the flow path
  • None of these
  • May be lateral mixing of fluid

Answer :Should not be any mixing along the flow path May be lateral mixing of fluid

The dispersion number of perfect mixed flow is:


Options are :

  • 0
  • > 150
  • ?
  • < 2100

Answer :?

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


Options are :

  • Film diffusion
  • Diffusion through ash layer
  • Either A, B or C
  • Chemical reaction

Answer :Diffusion through ash layer

An isothermal irreversible reaction is being carried out in an ideal tubular flow reactor. The conversion in this case will __________ with decrease in space time


Options are :

  • Decrease
  • Remain unchanged
  • Increase exponentially
  • Increase

Answer :Decrease

A consecutive reaction,

, is characterised by:


Options are :

  • Maxima in the concentration of B
  • Maxima in the concentration of A
  • High exothermicity
  • Maxima in the concentration of C

Answer :Maxima in the concentration of B

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