Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 3

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


Options are :

  • Constant
  • Neither A nor B
  • Both A and B
  • Conversion

Answer :Conversion

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 4

The time needed to achieve the same fractional conversion for particles of different sizes (d) when chemical reaction controls, is proportional to:


Options are :

  • d^(2)
  • d
  • d^(1.5)
  • ?d

Answer :d

Which of the following is an autocatalytic reaction ?


Options are :

  • Ammonia synthesis reaction
  • Photochemical reactions
  • Microbial fermentation reaction
  • Enzyme fermentation reaction

Answer :Microbial fermentation reaction

Which of the following is the most suitable for isothermal operation ?


Options are :

  • Back-mix reactor
  • Plug-flow reactor
  • Fixed bed reactor
  • Batch reactor

Answer :Back-mix reactor

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 5

Which of the following chemical reactions will be favoured by low pressure ?


A.

2HI

H2 + I2


B.

N2O2

2NO2


C.

N2 + O2

2NO


D.

None of these


Options are :

  • D
  • B
  • C
  • A

Answer :B

Which of the following is not endothermic in nature ?


Options are :

  • Gasification of carbon
  • Steam reforming of naphtha
  • Thermal cracking of fuel oil
  • Combustion of sulphur

Answer :Combustion of sulphur

The performance of a cascade of CSTR's can be improved by adding:


Options are :

  • More CSTR's in parallel
  • More CSTR's in series
  • A P.F. reactor in series
  • A P.F. reactor in parallel

Answer :More CSTR's in series

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 6

The equilibrium constant for the reversible reaction,

, is affected by the:


Options are :

  • Temperature of the system
  • Pressure of the system
  • Kinetics of the reaction
  • Presence or absence of inerts

Answer :Pressure of the system

Pick out the wrong statement:


Options are :

  • Slow chemical reactions have generally high values of activation energy
  • In general, the rate of a reaction becomes triple for every 10C rise in temperature
  • Molecularity of a reaction can not be zero but the order of a reaction can be zero
  • In a multistep reaction, the slowest step is the rate determining step

Answer :In general, the rate of a reaction becomes triple for every 10C rise in temperature

In a zero order reaction, reactants concentration does not change with time and the:


Options are :

  • Time for half change is independent of the initial concentration
  • Reaction rate is trebled when the initial concentration is trebled
  • Time for completion of the reaction is independent of the initial concentration
  • Time for half change is half the time taken for completion of the reaction

Answer :Time for half change is half the time taken for completion of the reaction

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 7

A gaseous reactant is introduced in a mixed reactor of 3 litres volume at the rate of 1 litre/second. The space time is __________ seconds


Options are :

  • 1
  • 32
  • 3
  • 1/3

Answer :3

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 8

The rate of reaction of a/an __________ reaction is not affected by temperature rise


Options are :

  • Zero order
  • Autocatalytic
  • Photochemical
  • Consecutive

Answer :Photochemical

The following half life data are available for the irreversible liquid phase reaction A

products:


The overall order of reaction is:


Options are :

  • 1.5
  • 2
  • 1
  • 0.5

Answer :1.5

For the gaseous reaction 2A

B, where the feed consists of 50 mole % A and 50 mole % inerts, the expansion factor is:


Options are :

  • - 0.25
  • 0
  • 1
  • - 0.5

Answer :- 0.25

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 9

The decomposition of A into B is represented by the exothermic reaction, A

2B. To achieve maximum decomposition, it is desirable to carry out the reaction:


Options are :

  • At high P and high T
  • At high P and low T
  • At low P and low T
  • At low P and high T

Answer :At low P and low T

For a __________ order chemical reaction,

, the fractional conversion of reactant 'A' is proportional to time


Options are :

  • Second
  • Third
  • Zero
  • First

Answer :Zero

With increase in the order of reaction (for all positive reaction orders), the ratio of the volume of mixed reactor to the volume of plug flow reactor (for identical feed composition, flow rate and conversion)


Options are :

  • Remains same
  • Decreases
  • Increases
  • Increases linearly

Answer :Increases

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


Options are :

  • The intrinsic activation energy E
  • ED/2
  • (E + ED)/2
  • (E + ED) where ED is activation due to diffusion

Answer :ED/2

In case of a __________ reactor, the composition in the reactor and at the exit of the reactor is the same


Options are :

  • Back-mix
  • Semi-batch
  • Batch
  • Tubular

Answer :Back-mix

Exothermic reactions are best carried out in:


Options are :

  • A plug flow reactor followed by CSTR
  • A CSTR
  • CSTR followed by a plug flow reactor
  • CSTR in series

Answer :CSTR followed by a plug flow reactor

In which of the following gaseous phase reversible reactions, the product yield can not be increased by the application of high pressure ?


A.

N2 + O2

2NO


B.

PCl3 + Cl2

PCl5


C.

N + 3H2

2NH3


D.

2SO2 + O2

2SO3


Options are :

  • C
  • A
  • D
  • B

Answer :A

The irreversible reaction is a special case of reversible reaction, if the:


Options are :

  • All of these
  • Equilibrium constant is 1
  • Conversion of the reactant at equilibrium condition is zero
  • Reactant concentration at equilibrium condition is zero

Answer :Reactant concentration at equilibrium condition is zero

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


Options are :

  • Unpredictable from the data
  • Increases
  • Decreases
  • Remains unaffected

Answer :Increases

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 1

A space velocity of 5 hr-1 means that:


Options are :

  • Five reactor volumes of feed (at specified conditions) are being fed into the reactor per hour
  • A fixed conversion of a given batch of feed takes 5 hours
  • Cent per cent conversion can be achieved in at least 5 hours
  • After every 5 hours, reactor is being filled with the feed

Answer :Five reactor volumes of feed (at specified conditions) are being fed into the reactor per hour

If helium is introduced in a reactor containing O2, SO2 and SO3 at equilibrium, so that total pressure increases while volume and temperature remains constant. In this case the dissociation of SO3 (as per Le Chatlier principle)


Options are :

  • Increases
  • Remains unaltered
  • Decreases
  • Changes unpredictably

Answer :Decreases

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


Options are :

  • Reversible endothermic
  • Reversible exothermic
  • Irreversible endothermic
  • Irreversible exothermic

Answer :Reversible endothermic

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 10

Collision theory gives the rate constant for bimolecular reaction as:


Options are :

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

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

A liquid decomposes by irreversible first order kinetics and the half life period of this reaction is 8 minutes. The time required for 75% conversion of the liquid will be __________ minutes


Options are :

  • 4
  • 12
  • 16
  • 8

Answer :16

The temperature dependence of reaction rate constant (K) by Arhenius law is given by:


Options are :

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

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

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:


Options are :

  • 3
  • 7/3
  • 6
  • 7

Answer :7

What is the order of chemical reaction

, if itis found that the reaction rate doubles on doubling the concentration of B and also the reaction rate doubles when the concentrations of both A & B were doubled and quandrupled when the concentrations of both B & C were doubled ?


Options are :

  • 3
  • 2
  • 4
  • 1

Answer :2

Backmixing is most predominant in:


Options are :

  • A well stirred batch reactor
  • A plug-flow reactor
  • CSTR's connected in series
  • A single CSTR

Answer :A single CSTR

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


Options are :

  • Reaction kinetics for single particle
  • All of these
  • Flow patterns of solids and fluid in the reactor
  • Size distribution of solids beingtreated

Answer :All of these

A non-catalytic chemical reaction of the type

is called a __________ reaction


Options are :

  • Series
  • Series-parallel
  • Parallel
  • None of these

Answer :Series-parallel

The molecularity and the order of reaction respectively, for the hydrolysis of methyl acetate in presence of acids are:


Options are :

  • 11 & 2
  • 2 & 1
  • 1 & 1
  • 2 && 2

Answer :2 & 1

Half-life period for a first order reaction is __________ the initial concentration of the reactant


Options are :

  • None of these
  • Independent of
  • Inversely proportional to
  • Directly proportional to

Answer :Independent of

For the liquid phase parallel reactions


R, rR = K1.CA2; E1 = 80 KJ/mole

S, 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:


Options are :

  • Low temperature in a CSTR
  • Low temperature in a PFR
  • High temperature in a PFR
  • High temperature in a CSTR

Answer :High temperature in a PFR

The unit of frequency factor in Arhenious equation is:


Options are :

  • Dimensionless
  • Same as that of rate constant
  • Same as that of activation energy
  • None of these

Answer :Same as that of rate constant

Consider a reversible exothermic reaction in a plug flow reactor. The maximum and minimum permissible temperatures are Tmax and Tmin respectively. Which of the following temperature (T) profiles will require the shortest residence time to achieve the desired conversion:


A.


B.


C.


D.


Options are :

  • D
  • C
  • B
  • A

Answer :B

A Catalyst:


Options are :

  • None of these
  • Shortens the time to reach the equilibrium
  • Changes the equilibrium constant of the reaction
  • Increases the equilibrium concentration of the product

Answer :Shortens the time to reach the equilibrium

Velocity of a chemical reaction:


Options are :

  • None of these
  • Increases with increase of pressure of reactants for all reactions
  • Decreases with increase of reactant concentration
  • Decreases with increase in temperature

Answer :None of these

Reaction of benzene with chlorine gas to produce tri-chlorobenzene exemplifies a/an __________ reaction


Options are :

  • Elementary
  • None of these
  • Parallel
  • Consecutive

Answer :Consecutive

Pick out the wrong statement:


Options are :

  • A very high value of equilibrium constant, K (K >> 1) indicates that the reaction is practically irreversible in nature
  • Non-ideal flow takes place in reactors due to recycling, channeling or by creation of stagnant regions
  • A particular chemical reaction is more temperature sensitive at low temperatures
  • The intercept of the Arrhenious plot is called the 'activation energy'

Answer :The intercept of the Arrhenious plot is called the 'activation energy'

Find a mechanism that is consistent with the rate equation and reaction given below:

2A + B

A2B, ( - rA) = k.CA.CB


A.

A + B

AB ; AB + A A2B


B.

A + B

AB;AB + A A2B


C.

A + A

AA;AA + B A2B


D.

A + A

AA;AA + B A2B


Options are :

  • B
  • A
  • C
  • D

Answer :D

If n = overall order of a chemical reaction. a = initial concentration of reactant. t = time required to complete a definite fraction of the reaction

Then pick out the correct relationship:


A.


B.


C.


D.

t ? a^(n)


Options are :

  • C
  • B
  • D
  • A

Answer :B

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