Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 5

For reaction, P + 2

3R, molar rate of consumption of P is:


Options are :

  • 2/3rd of that of Q
  • Double of that of Q
  • Same as that of Q
  • Half of that of Q

Answer :Half of that of Q

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 6

A first order reaction A

B occurs in an isothermal porous catalyst pellet of spherical shape. If the concentration of A at the centre of the pellet is much less than at the external surface, the process is limited by:


Options are :

  • None of the above
  • External mass transfer
  • Reaction
  • Diffusion within the pellet

Answer :Diffusion within the pellet

In a chemical reaction, repesented by,

, it is observed that the
(i) rate of reaction increases by a factor of 4 on doubling the concentration of the reactant.
(ii) rate of reaction increases by a factor of 9 on trebling the concentration of the reactant.

Then the rate of the reaction is proportional to (where, CA = contentration of the reactant)


Options are :

  • CA3
  • CA2
  • CA3
  • CA

Answer :CA2

Catalyst is a substance, which __________ chemical reaction


Options are :

  • Can either increase or decrease the speed of a
  • Alters the value of equilibrium constant in a reversible
  • Decreases the speed of a
  • Increases the speed of a

Answer :Can either increase or decrease the speed of a

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 7

Which of the following holds good for an elementary reaction,

?


Options are :

  • The rate of disappearance of 'Y' is equal to the rate of disappearance of 'X'
  • The rate of disappearance of 'X' is equal to the rate of appearance of 'Z'
  • Three times the rate of disappearance of 'X' is equal to the rate of appearance of 'Z'
  • The rate of disappearance of 'Y' is equal to the rate of appearance of 'Z'

Answer :Three times the rate of disappearance of 'X' is equal to the rate of appearance of 'Z'

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:


Options are :

  • 0.16
  • 0.152
  • 0.136
  • 0.144

Answer :0.144

Bulk diffusion in catalyst pore __________ with increase in pressure


Options are :

  • Increases exponentially
  • Remains unchanged
  • Increases
  • Decreases

Answer :Decreases

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 8

B.E.T. method of finding out surface area of a catalyst, uses the extension of __________ isotherm


Options are :

  • None of these
  • Tempkin
  • Langmuir
  • Freundlich

Answer :Langmuir

If pore diffusion is the controlling step in a solid catalysed reaction, the catalyst:


Options are :

  • Porosity is of less importance
  • Porosity is very important
  • None of these
  • Internal surface area is utilised efficiently

Answer :Porosity is of less importance

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


Options are :

  • 4
  • 16
  • 8
  • 2

Answer :16

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 9

What is the dispersion number for a CSTR ?


Options are :

  • 0
  • 1
  • ?
  • < 1

Answer :?

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


Options are :

  • 0.875
  • Data insufficient to calculate
  • 0.5
  • 0.425

Answer :0.875

__________ resistance is not involved in the combustion of a carbon particle


Options are :

  • Ash
  • Gas film
  • None of these
  • Chemical reaction

Answer :Ash

Pick out the correct statement:


Options are :

  • The rate constant for a first order reaction does not change on changing the concentration units
  • A chemical reaction accompanied by evolution of heat is called an endother-mic reaction
  • A chemical reaction accompanied by absorption of heat is called an exothermic reaction
  • Chemical equilibrium state is dynamic in nature

Answer :The rate constant for a first order reaction does not change on changing the concentration units

Pick out the wrong statement:


Options are :

  • In a first order reaction, A products; the reaction becomes slower as it proceeds, because the concentration of A decreases and the rate is proportional to the concentration of A
  • If the rate of an irreversible reaction, A + B 2C is k.CA.CB, then the reaction is always elementary
  • According to the penetration theory, the mass transfer co-efficient decreases, if the exposure time of an eddy to the solute decreases
  • Transition state theory approaches the problem of calculating reaction rates by concentrating on the idea of activated complexes

Answer :According to the penetration theory, the mass transfer co-efficient decreases, if the exposure time of an eddy to the solute decreases

Cold shot cooling is only practical when the feed temperature is __________ than the reaction temperature


Options are :

  • Much lower
  • Higher
  • Much higher
  • Lower

Answer :Much lower

The conversion for a first order liquid phase reaction. A

B in a CSTR is 50%. If another CSTR of the same volume is connected in series, then the % conversion at the exit of the second reactor will be:


Options are :

  • 100
  • 75
  • 90
  • 60

Answer :75

The enzyme which can catalyse the conversion of glucose to ethyl alcohol is:


Options are :

  • Invertase
  • Diastase
  • Maltase
  • Zymase

Answer :Zymase

Recycling back of outlet stream to the reactor from an ideal CSTR carrying out a first order liquid phase reaction will result in __________ in conversion


Options are :

  • Increase
  • Decrease
  • No change
  • Either A or B; depends on the type of reaction

Answer :No change

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 1

Which of the following factors control the deactivation of a porous catalyst pellet ?


Options are :

  • Form of surface attack by poison
  • All of these
  • Decay reactions
  • Pore diffusion

Answer :All of these

The sequence in which three CSTR's of volumes 5, 10 and 15 m3 will be connected in series to obtain the maximum production in a second order irreversible reaction is:


Options are :

  • 10, 5, 15
  • 10, 15, 5
  • 5, 10, 15
  • 15, 10, 5

Answer :15, 10, 5

Photo-chemical reactions occur in presence of:


Options are :

  • Darkness
  • Monochromatic radiation only
  • Sunlight
  • Solid catalysts

Answer :Sunlight

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 10

Equilibrium of a chemical reaction as viewed by kinetics is a __________ state


Options are :

  • None of these
  • Dynamic unsteady
  • Dynamic steady
  • Static steady

Answer :Dynamic steady

A batch reactor suffers from following disadvantage:


Options are :

  • High labour and handling cost
  • High shutdown time requirement for emptying, cleaning and refilling
  • Poor product quality control
  • All of these

Answer :All of these

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


Options are :

  • 0.693?
  • ?/0.693
  • 2?
  • 0.5?

Answer :2?

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 11

If Thiele modulus is __________ , then the pore diffusion resistance in a catalyst may be considered as negligible


Options are :

  • < 0.5
  • 0
  • > 0.5
  • ?

Answer :< 0.5

The use of space time is preferred over the mean residence time in the design of a/an:


Options are :

  • CSTR
  • Ideal tubular-flow reactor
  • Batch reactor
  • Slurry reactor

Answer :Ideal tubular-flow reactor

When an exothermic reversible reaction is conducted adiabatically, the rate of reaction:


Options are :

  • Continuously increases
  • Passes through a minimum
  • Passes through a maximum
  • Continuously decreases

Answer :Passes through a maximum

Chemical Reaction Engineering MCQ Practice Questions (Chem) Set 2

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.) ?


Options are :

  • 1/3
  • 1/2
  • 2/3
  • 2

Answer :2/3

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 ?


Options are :

  • 0
  • 3
  • 1
  • 2

Answer :0

An endothermic second order reaction is carried out in an adiabatic plug flow reactor. The rate of heat generation is:


Options are :

  • Maximum at the inlet of the reactor
  • Constant throughout the reactor
  • Maximum at the exit of the reactor
  • Maximum at the centre of the reactor

Answer :Maximum at the inlet of the reactor

The importance of diffusion in a catalyst are increased by:


Options are :

  • An active surface of the catalyst
  • Small pore diameter
  • Large catalyst particle size
  • All of these

Answer :All of these

Half life period of a chemical reaction is proportional to CA0-1 , if the reaction is of __________ order


Options are :

  • Third
  • Second
  • Zero
  • First

Answer :Second

The heat of reaction:


Options are :

  • Depends on both pressure and mechanism of reaction
  • Depends on the mechanism of reaction only
  • Depends on the pressure only
  • Is independent of the mechanism of reaction

Answer :Is independent of the mechanism of reaction

The equilibrium constant K of a chemical reaction depends on:


Options are :

  • Temperature only
  • Ratio of reactants
  • Temperature and pressure
  • Pressure only

Answer :Temperature only

The exit age distribution curve E(t) for an ideal CSTR with the average residence time, ?, is given by:


A.

e-t/?


B.


C.

1 - e-t/?


D.


Options are :

  • A
  • C
  • D
  • B

Answer :B

A liquid phase reaction is to be carried out under isothermal conditions. The reaction rate as a function of conversion has been determined experimentally and is shown in the figure given below.

What choice of reactor or combination of reactors will require the minimum overall reactor volume, if a conversion of 0.9 is desired ?


Options are :

  • PFR followed by a CSTR
  • PFR followed by a CSTR followed by a PFR
  • CSTR followed by a PFR followed by a CSTR
  • CSTR followed by a PFR

Answer :PFR followed by a CSTR followed by a PFR

In case of staged packed bed reactors carrying out exothermic reaction, use:


Options are :

  • High recycle for pure gas
  • Cold shot operations for a dilute solution requiring large preheating to bring the stream upto the reaction temperature
  • All of these
  • Plug flow for dilute liquid requiring no large preheating of feed

Answer :All of these

Autocatalytic reactions are best carried out in a:


Options are :

  • Recycle reactor
  • CSTR
  • CSTR in series
  • Plug flow reactor

Answer :Recycle reactor

Shift conversion reaction:


Options are :

  • Converts N2 and H2 into NH3
  • Is non-catalytic
  • Is highly exothermic
  • Converts CO to CO2 with steam

Answer :Converts CO to CO2 with steam

Pick out the wrong statement:


Options are :

  • Presence of inerts affects the equilibrium conversion of reactants in a chemical reaction
  • Use of different catalysts in a reversible catalytic chemical reaction does not change the equilibrium composition
  • Alumina is added as a promoter to iron catalyst in ammonia synthesis reaction
  • Activation energy for a reaction is obtained from the intercept of the Ar-rhenious plot

Answer :Activation energy for a reaction is obtained from the intercept of the Ar-rhenious plot

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


Options are :

  • Is maximum at the inlet of the reactor
  • Is maximum at the exit of the reactor
  • Goes through a maximum along the length of the reactor
  • Goes through a minimum along the length of the reactor

Answer :Is maximum at the inlet of the reactor

For a __________ order reaction, the units of rate constant and rate of reaction are the same


Options are :

  • Fractional
  • Second
  • Zero
  • First

Answer :Zero

In a CSTR __________ varies with time


Options are :

  • Both A and B
  • None of these
  • Concentration
  • Reaction rate

Answer :None of these

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


Options are :

  • Threshold
  • Thermal
  • Binding
  • Activation

Answer :Activation

Comment / Suggestion Section
Point our Mistakes and Post Your Suggestions