Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 6

Which of the following is not a unit of reaction rate ?


Options are :

  • Moles for med/(surface of catalyst) (time)
  • Mole formed/volume of catalyst) (time)
  • None of these
  • Moles formed/volume of reactor) (time)

Answer :None of these

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 7

__________ gas is normally employed in B.E.T.method of finding out the surface area of catalyst


Options are :

  • He
  • N2
  • H2
  • CO2

Answer :N2

For multiple reactions, the flow pattern within the vessel affects the:


Options are :

  • Distribution of reaction products
  • Size requirement
  • None of these

Answer :Distribution of reaction products Size requirement

Brunaur, Emmet and Teller (BET) equation is used to determine the specific surface area of a porous particle but not the pore volume & the porosity of the catalyst bed

Which of the following postulates is not used to derive BET equation ?


Options are :

  • Langmuir's assumption applies to every adsorbed layer
  • There is no dynamic equilibrium between successive layer
  • The adsorbed layer may be polymolecular in thickness and the heat of adsorption in each layer (except the first one) is involved in each of the evaporation process
  • None of these

Answer :There is no dynamic equilibrium between successive layer

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 8

As the chemical reaction proceeds, the rate of reaction:


Options are :

  • Remains same
  • Increases
  • May increase or decrease depending on the type of reaction
  • Decreases

Answer :Decreases

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


Options are :

  • 6
  • 3
  • 4
  • 8

Answer :4

For the reaction, A + B

2B + C


Options are :

  • rA = -rB
  • rA = rB/2
  • rA = rB
  • rA = 2rB

Answer :rA = -rB

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 9

Pure A in gas phase enters a reactor 50% of this A is converted to B through the reaction, A

3B. Mole fraction of A in the exit stream is:


Options are :

  • 1/2
  • 1/5
  • 1/3
  • 1/4

Answer :1/3

The rate expression for the gaseous phase reaction, CO + 2H2

CH3OH, is given by,

Which of the following is not possible ?


Options are :

  • ? = 1, ? = 2, ? = 1
  • ? = 1/2, ? = 1, ? = 1/2
  • ? = 1, ? = 1, ? =1
  • ? = 1/3, ? = 2/3, ? = 1/3

Answer :? = 1, ? = 1, ? =1

The ratio of moles of a reactant converted into the desired product to that converted into unwanted product is called:


Options are :

  • Operational yield
  • Selectivity
  • None of these
  • Relative yield

Answer :Selectivity

Participation of __________ is involved in the occurrence of a chemical reaction


Options are :

  • Electrons
  • Neutrons
  • Protons
  • None of these

Answer :Electrons

The experimentally determined overall order of the reaction, A + B

C + D, is two. Then the:


Options are :

  • Molecularity of the reaction is 2, but the reaction may not be elementary
  • Reaction is elementary with a molecularity of 2
  • Reaction is elementary but the molecularity may not be 2
  • Reaction may be elementary with molecularity of 2

Answer :Reaction is elementary with a molecularity of 2

Promoter:


Options are :

  • Alters the position of equilibrium in a reversible reaction
  • Initiates a chemical reaction and is a catalyst by itself
  • All of these
  • Increases the number of active centres by increasing the unevenness of catalyst surface and by creating discontinuities in the crystals

Answer :Increases the number of active centres by increasing the unevenness of catalyst surface and by creating discontinuities in the crystals

Which one is the rate controlling step in a solid-gas non-catalytic reaction occurring at very high temperature ?


Options are :

  • Ash layer diffusion
  • Chemical reaction
  • Film diffusion
  • Pore diffusion

Answer :Film diffusion

Transition state theory gives the rate constant as:


Options are :

  • K ? e^(E/RT)
  • K ? T . e^(-E/RT)
  • K ? e^(-E/RT)
  • K ? ?T . e^(-E/RT)

Answer :K ? T . e^(-E/RT)

Maximum equilibrium conversion for endothermic reaction is obtained at the __________ temperature


Options are :

  • Intermediate
  • Room
  • Highest possible
  • Lowest possible

Answer :Highest possible

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 1

In solid catalysed reactions the diffusional effects are more likely to affect the overall rate of reaction for:


Options are :

  • Fast reactions in catalyst of small pore diameter
  • Slow reactions in catalyst of small pore diameter
  • Fast reaction in catalyst of large pore diameter
  • Slow reactions in catalyst of large pore diameter

Answer :Slow reactions in catalyst of small pore diameter

In Langmuir treatment of adsorption:


Options are :

  • Whole surface of the catalyst does not have the same activity for adsorption and there is attraction between the adsorbed molecule
  • All the adsorption does not take place by the same mechanism
  • Extent of adsorption is more than one complete monomolecular layer on the surface
  • Whole surface of the catalyst is essentially uniform and the adsorbed molecule has no effect on the rate of adsorption per site

Answer :Whole surface of the catalyst is essentially uniform and the adsorbed molecule has no effect on the rate of adsorption per site

Organic catalysts differ from the inorganic catalyst in the sense that the former is:


Options are :

  • Active at cryogenic temperatures only
  • Proteinous in nature
  • Prohibitively costly
  • Active at very high temperature only

Answer :Proteinous in nature

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 10

A first order reaction is to be treated in a series of two mixed reactors. The total volume of the two reactors is minimum, when the reactors are:


Options are :

  • of such size that the ratio of their volumes is < 5
  • of different sizes
  • Equal in size
  • None of these

Answer :Equal in size

A second order liquid phase reaction, A

B, is carried out in a mixed flow reactor operated in semi batch mode (no exit stream). The reactant A at concentration CAF is fed to the reactor at a volumetric flow rate of F. The volume of the reacting mixture is V and the density of the liquid mixture is constant

The mass balance for A is:


A.


B.


C.


D.


Options are :

  • D
  • B
  • C
  • A

Answer :D

Vegetable oils are hydrogenated in a __________ reactor


Options are :

  • Homogeneous catalytic
  • Slurry
  • None of these
  • Plug flow

Answer :Slurry

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 11

A trickle bed reactor is the one, which


Options are :

  • Has altogether three streams either entering or leaving
  • Processes three reactants with same flow rate
  • Processes three reactants at different flow rates
  • Employs all the three phases (i.e.. .solid, liquid and gas)

Answer :Employs all the three phases (i.e.. .solid, liquid and gas)

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


Options are :

  • 0.5
  • 0
  • 0.1
  • 1

Answer :0.1

Chemical reaction rate of a component depends upon the:


Options are :

  • Composition of the component only
  • Temperature of the system
  • Pressure of the system
  • All of these

Answer :All of these

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 2

In a continuous flow stirred tank reactor, the composition of the exit stream:


Options are :

  • Is different than that in the reactor
  • None of these
  • Is same as that in the reactor
  • Depends upon the flow rate of inlet stream

Answer :Is same as that in the reactor

The response curve for a step input signal from a reactor is called C-curve. The variance of C-curve in a 'tanks in series model' comprising of 'm' tanks is equal to:


Options are :

  • m^(2)
  • m
  • 1/m
  • ?m

Answer :1/m

In a first order reaction, the time required to reduce the concentration of reactant from 1 mole/litre to 0.5 mole/litre will be __________ that required to reduce it from 10 moles/litre to 5 moles/litre in the same volume


Options are :

  • Same as
  • More than
  • Data insufficient; can't be predicted
  • Less than

Answer :Same as

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 3

The rate constant of a reaction is a function of the:


Options are :

  • Temperature of the system
  • Extent of reaction
  • Time of reaction
  • Initial concentration of the reactants

Answer :Temperature of the system

If 'n' is the order of reaction, then unit of rate constant is:


Options are :

  • None of these
  • 1/(time)(concentration)^(n - 1)
  • (time)^(-1) (concentration)^(n - 1)
  • (time)^(n - 1) (concentration)

Answer :1/(time)(concentration)^(n - 1)

Mean residence time is equal to the space time, when:


Options are :

  • The feed rate is measured at temperature and pressure in the reactor
  • All of these
  • The temperature, pressure and the density of reaction mixture remains constant throughout the reactor
  • There is no change in number of moles in gaseous reaction

Answer :All of these

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


Options are :

  • Exothermic
  • Autocatalytic
  • Autothermal
  • Endothermic

Answer :Autocatalytic

With increase in temperature, the equilibrium conversion of a reversible exothermic reaction:


Options are :

  • Decreases linearily with temperature
  • Remains unaffected
  • Increases
  • Decreases

Answer :Decreases

Batch process is preferred over continuous process, when the:


Options are :

  • Same equipment can not be used for several processes of the same nature
  • Sales demand of product is not steady
  • All of these
  • Product yields and quality can not be achieved in continuous process, because of long residence time

Answer :All of these

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 ?


Options are :

  • 0.152
  • 0.253
  • 0.338
  • 0.637

Answer :0.338

Pick out the wrong statement:


Options are :

  • A catalyst is specific in reaction
  • A catalyst remains unchanged in chemical composition at the end the reaction
  • A catalyst initiates a reaction
  • A catalyst does not alter the final position of equilibrium in a reversible reaction

Answer :A catalyst initiates a reaction

The rate of the heterogenous catalytic reaction A(g) + B(g)

C(g) is given by -rA = k.KA.pA.PB/(1 + KA.PA + Kc.pc), where KA and Kc are the adsorption equilibrium constants. The rate controlling step for this reaction is:


Options are :

  • Surface reaction between absorbed A and absorbed B
  • Surface reaction between A in the gas phase and absorbed B
  • Absorption of A
  • Surface reaction between absorbed A and B in the gas phase

Answer :Surface reaction between absorbed A and B in the gas phase

On application of pressure to the equilibrium system, ice

water ; which of the following phenomenon will occur ?


Options are :

  • More ice will be formed
  • Water will evaporate
  • More water will be formed
  • Equilibrium will not be attained

Answer :More water will be formed

'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


Options are :

  • 1/V
  • V/n
  • V.n
  • V

Answer :V

For the same residence time, which one will give the maximum conversion ?


Options are :

  • Single stirred tank (v = 5 litres)
  • Single tubular flow reactor (v = 5 litres)
  • Two stirred tank (each of 2.5 litres) in series
  • Stirred tank followed by tubular flow reactor (each of 2.5 litres)

Answer :Single tubular flow reactor (v = 5 litres)

Which of the following does not produce a change in the value of rate constant of a reaction ?


Options are :

  • Pressure
  • Temperature
  • None of these
  • Concentration and catalyst

Answer :Concentration and catalyst

In a semi-batch reactor:


Options are :

  • Velocity of reaction can be controlled
  • Both the reactants flow counter-currently
  • Residence time is constant
  • Maximum conversion can be controlled

Answer :Velocity of reaction can be controlled

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:


Options are :

  • CSTR of volume V
  • PFR of volume V
  • CSTR of volume V/X
  • PFR of volume V/X

Answer :PFR of volume V

In a reversible reaction, a catalyst increases the rate of forward reaction:


Options are :

  • Only
  • And the backward reaction equally
  • And decreases that of the backward reaction
  • To a greater extent than that of the backward reaction

Answer :And the backward reaction equally

The size of plug flow reactor (PFR) for all positive reaction orders and for any given duty, is __________ that of mixed reactor:


Options are :

  • Greater than
  • Equal to
  • Unpredictable from the data
  • Smaller than

Answer :Smaller than

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