When all the limiting reactant is consumed in the reaction, the operational yield __________ the relative yield.

Can be either greater or smaller than (depends on the type of reaction)

Molecularity of a reaction

Is always equal to the overall order of reaction

May not be equal to the order of reaction

Can’t have a fractional value

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

Data insufficient, cant be predicted

Large reactor followed by smaller one

Smaller reactor followed by larger one

Either of the arrangement (A) or (B) will give the same yield

Data insufficient, cant be predicted

An autothermal reactor is

Most suitable for a second order reaction

Most suitable for a reversible reaction

Completely self-supporting in its thermal energy requirements

Sulphuric acid is used as a catalyst in the

Gas phase oxidation of SO2 in chamber process

A trickle bed reactor is the one, which

Has altogether three streams either entering or leaving

Processes three reactants at different flow rates

Processes three reactants with same flow rate

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

With decrease in temperature, the equilibrium conversion of a reversible endothermic reaction

Increases linearly with temperature

The energy balance equation over a tubular reactor under transient conditions is

A non-linear partial differential equation

An ordinary non-linear differential equation

An algebraic differential equation

A linear partial differential equation

A non-linear partial differential equation

Exothermic reactions are best carried out in

A plug flow reactor followed by CSTR

CSTR followed by a plug flow reactor

The experimentally determined overall order of the reaction, A + B → C + D, is two. Then the

Molecularity of the reaction is 2, but the reaction may not be elementary

Reaction is elementary with a molecularity of 2

Molecularity of the reaction is 2, but the reaction may not be elementary

Reaction may be elementary with molecularity of 2

Reaction is elementary but the molecularity may not be 2

Enzymes are destroyed, when the

Reactants concentration is very high

Reactants concentration is very low

Reaction rate is independent of the reactants concentration

For a zero order chemical reaction, the

Half life period is directly proportion to the initial concentration of the reactants

Plot of products concentration with time is a straight line through the origin

Products concentration increases linearly with time

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

Maximum at the exit of the reactor

Maximum at the inlet of the reactor

Maximum at the exit of the reactor

Maximum at the centre of the reactor

Constant throughout the reactor

In the reversible reaction of the type, A + B ⇌ AB, in general

The combination reaction will be endothermic, while the dissociation reaction will be exothermic

Both forward and backward reactions will be exothermic

Neither of the reactions will be endothermic

The combination reaction will be exothermic, while the dissociation reaction will be endothermic

The combination reaction will be endothermic, while the dissociation reaction will be exothermic

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

Form of surface attack by poison

Employs mixing in axial direction only

Is same as ideal stirred tank reactor

Employs mixing in axial direction only

Is most suitable for gas phase reaction

A batch reactor is suitable for

Obtaining uniform polymerisation products in highly exothermic reactions

Achieving cent percent conversion of reactants into products

Large scale gaseous phase reactions

Obtaining uniform polymerisation products in highly exothermic reactions

Photochemical reaction rate does not depend significantly on temperature, because

The energy of reacting molecules exceeds the activation energy by absorption of light

In an ideal mixed reactor (at steady state), the

Space time is equivalent to holding time for constant density systems

Composition throughout the reactor remains same

Exit stream has the same composition as the fluid within the reactor

The importance of diffusion in a catalyst are increased by

An active surface of the catalyst

1443 + Mcqs in Chemical Reaction Engineering Page 23 McqOptions

1101.	In flow reactors, the performance equations interrelate the rate of reaction to the
A.	Feed rate
B.	Reactor volume
C.	Extent of reaction
D.	All (A), (B) and (C)
Answer» E.

Discussion

1102.	A multiple reaction may be classified as a __________ reaction.
A.	Consecutive or side
B.	Parallel or side
C.	Mixed
D.	All (A), (B) and (C)
Answer» E.

Discussion

1103.	When all the limiting reactant is consumed in the reaction, the operational yield __________ the relative yield.
A.	Is greater than
B.	Is smaller than
C.	Equals
D.	Can be either greater or smaller than (depends on the type of reaction)
Answer» D. Can be either greater or smaller than (depends on the type of reaction)

Discussion

1104.	Molecularity of a reaction
A.	Is always equal to the overall order of reaction
B.	May not be equal to the order of reaction
C.	Can’t have a fractional value
D.	Both (B) and (C)
Answer» E.

Discussion

1105.	Which of the following is an independent variable for a batch tank reactor with uniform concentration and temperature?
A.	Time
B.	Useful volume of the tank
C.	Diameter of the reactor
D.	None of these
Answer» B. Useful volume of the tank

Discussion

1106.	A balanced chemical reaction equation conforms to the law of
A.	Conservation of mass
B.	Avogadro’s hypothesis
C.	Gaseous volumes
D.	None of these
Answer» B. Avogadro’s hypothesis

Discussion

1107.	Enzymes (a protein) are catalysts found in organisms. Its efficiency of catalysing a reaction is due to its capacity to lower the activation energy of the reaction. The enzyme ptyalin used for food digestion is present in
A.	Blood
B.	Saliva
C.	Intestine
D.	Gland
Answer» C. Intestine

Discussion

1108.	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
Answer» C. N2 + O2 ⇌ 2NO

Discussion

1109.	A reaction in which one of the products of reaction acts as a catalyst is called a/an __________ reaction.
A.	Catalytic
B.	Autocatalytic
C.	Photochemical
D.	None of these
Answer» C. Photochemical

Discussion

1110.	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
A.	0.80
B.	1.33
C.	1.60
D.	2.67
Answer» D. 2.67

Discussion

1111.	When the density of the reaction mixture is constant in a chemical reaction, the ratio of the mean residence time to space time is
A.	> 1
B.	< 1
C.	1
D.	0
Answer» D. 0

Discussion

1112.	The performance of a cascade of CSTR's can be improved by adding
A.	A P.F. reactor in series
B.	A P.F. reactor in parallel
C.	More CSTRs in series
D.	More CSTRs in parallel
Answer» D. More CSTRs in parallel

Discussion

1113.	The rate of a chemical reaction is almost doubled for every 10°C rise in temperature. The rate will increase __________ times, if the temperature rises from 10 to 100°C.
A.	256
B.	512
C.	112
D.	612
Answer» C. 112

Discussion

1114.	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, cant be predicted
Answer» D. Data insufficient, cant be predicted

Discussion

1115.	An autothermal reactor is
A.	Most suitable for a second order reaction
B.	Most suitable for a reversible reaction
C.	Completely self-supporting in its thermal energy requirements
D.	Isothermal in nature
Answer» D. Isothermal in nature

Discussion

1116.	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

1117.	Sulphuric acid is used as a catalyst in the
A.	Hydrogenation of oils
B.	Gas phase oxidation of SO2 in chamber process
C.	Alkylation of hydrocarbons
D.	None of these
Answer» D. None of these

Discussion

1118.	A trickle bed reactor is the one, which
A.	Has altogether three streams either entering or leaving
B.	Processes three reactants at different flow rates
C.	Processes three reactants with same flow rate
D.	Employs all the three phases (i.e. solid, liquid and gas)
Answer» E.

Discussion

1119.	In a chemical reaction, __________ are conserved.
A.	Ions
B.	Masses
C.	Atoms
D.	Both (B) & (C)
Answer» E.

Discussion

1120.	The rate of reaction of a/an __________ reaction is not affected by temperature rise.
A.	Autocatalytic
B.	Photochemical
C.	Consecutive
D.	Zero order
Answer» C. Consecutive

Discussion

1121.	With decrease in temperature, the equilibrium conversion of a reversible endothermic reaction
A.	Decreases
B.	Increases
C.	Remain unaffected
D.	Increases linearly with temperature
Answer» B. Increases

Discussion

1122.	The energy balance equation over a tubular reactor under transient conditions is
A.	An ordinary non-linear differential equation
B.	An algebraic differential equation
C.	A linear partial differential equation
D.	A non-linear partial differential equation
Answer» D. A non-linear partial differential equation

Discussion

1123.	Ionic reactions occur in
A.	Solid state only
B.	Liquid state only
C.	Solutions
D.	Any state
Answer» D. Any state

Discussion

1124.	Exothermic reactions are best carried out in
A.	A CSTR
B.	CSTR in series
C.	A plug flow reactor followed by CSTR
D.	CSTR followed by a plug flow reactor
Answer» E.

Discussion

1125.	N' plug flow reactors in series with a total volume 'V' gives the same conversion as a single plug flow reactor of volume 'V' for __________ order reactions.
A.	First
B.	Second
C.	Third
D.	Any
Answer» E.

Discussion

1126.	The experimentally determined overall order of the reaction, A + B → C + D, is two. Then the
A.	Reaction is elementary with a molecularity of 2
B.	Molecularity of the reaction is 2, but the reaction may not be elementary
C.	Reaction may be elementary with molecularity of 2
D.	Reaction is elementary but the molecularity may not be 2
Answer» B. Molecularity of the reaction is 2, but the reaction may not be elementary

Discussion

1127.	Enzymes are destroyed, when the
A.	Temperature is very high
B.	Reactants concentration is very high
C.	Reactants concentration is very low
D.	Reaction rate is independent of the reactants concentration
Answer» B. Reactants concentration is very high

Discussion

1128.	Backmixing is most predominant in
A.	A well stirred batch reactor
B.	A plug-flow reactor
C.	A single CSTR
D.	CSTRs connected in series
Answer» D. CSTRs connected in series

Discussion

1129.	________ is the response curve for a step input signal from a reactor
A.	S-curve
B.	C-curve
C.	I-curve
D.	None of these
Answer» C. I-curve

Discussion

1130.	For the chemical reaction X → Y, it is observed that, on doubling the concentration of 'X', the reaction rate quadruples. If the reaction rate is proportional to Cx n , then what is the value of „n‟?
A.	1/4
B.	2
C.	4
D.	16
Answer» D. 16

Discussion

1131.	An imbalanced chemical reaction equation is against the law of
A.	Multiple proportion
B.	Conservation of mass
C.	Constant proportion
D.	None of these
Answer» C. Constant proportion

Discussion

1132.	For a zero order chemical reaction, the
A.	Half life period is directly proportion to the initial concentration of the reactants
B.	Plot of products concentration with time is a straight line through the origin
C.	Products concentration increases linearly with time
D.	All (A), (B) and (C)
Answer» E.

Discussion

1133.	An endothermic second order reaction is carried out in an adiabatic plug flow reactor. The rate of heat generation is:
A.	Maximum at the inlet of the reactor
B.	Maximum at the exit of the reactor
C.	Maximum at the centre of the reactor
D.	Constant throughout the reactor
Answer» B. Maximum at the exit of the reactor

Discussion

1134.	Which of the following is a controlling factor in very fast heterogeneous reaction?
A.	Heat and mass transfer effects
B.	Pressure
C.	Temperature
D.	Composition of reactant
Answer» B. Pressure

Discussion

1135.	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.
A.	At high P and high T
B.	At low P and high T
C.	At low P and low T
D.	At high P and low T
Answer» D. At high P and low T

Discussion

1136.	In case of physical adsorption, the heat of adsorption is of the order of __________ kcal/kg.mole.
A.	100
B.	1000
C.	10000
D.	100000
Answer» C. 10000

Discussion

1137.	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

1138.	In the reversible reaction of the type, A + B ⇌ AB, in general
A.	Both forward and backward reactions will be exothermic
B.	Neither of the reactions will be endothermic
C.	The combination reaction will be exothermic, while the dissociation reaction will be endothermic
D.	The combination reaction will be endothermic, while the dissociation reaction will be exothermic
Answer» D. The combination reaction will be endothermic, while the dissociation reaction will be exothermic

Discussion

1139.	The knowledge of initial concentration and rate constant is necessary to determine the half life time of a reaction of __________ order.
A.	Zero
B.	First
C.	Second
D.	None of these
Answer» D. None of these

Discussion

1140.	For a solid catalysed chemical reaction, the effectiveness of solid catalyst depends upon the __________ adsorption.
A.	Physical
B.	Chemical
C.	Both (A) and (B)
D.	Neither (A) nor (B)
Answer» C. Both (A) and (B)

Discussion

1141.	Which of the following factors control the deactivation of a porous catalyst pellet?
A.	Decay reactions
B.	Pore diffusion
C.	Form of surface attack by poison
D.	All (A), (B) and (C)
Answer» E.

Discussion

1142.	A backmix reactor
A.	Is same as plug-flow reactor
B.	Is same as ideal stirred tank reactor
C.	Employs mixing in axial direction only
D.	Is most suitable for gas phase reaction
Answer» C. Employs mixing in axial direction only

Discussion

1143.	Carbon particles accumulated on the catalyst used in the gas oil cracking lies in the category of __________ poison.
A.	Deposited
B.	Chemisorbed
C.	Selectivity
D.	Stability
Answer» B. Chemisorbed

Discussion

1144.	A batch reactor is suitable for
A.	Achieving cent percent conversion of reactants into products
B.	Large scale gaseous phase reactions
C.	Liquid phase reactions
D.	Obtaining uniform polymerisation products in highly exothermic reactions
Answer» D. Obtaining uniform polymerisation products in highly exothermic reactions

Discussion

1145.	For an ideal plug flow reactor, the value of Peclet number is
A.	0
B.	1
C.	10
D.	∞
Answer» B. 1

Discussion

1146.	Photochemical reaction rate does not depend significantly on temperature, because
A.	It is a reversible reaction
B.	It is an exothermic reaction
C.	The energy of reacting molecules exceeds the activation energy by absorption of light
D.	None of these
Answer» D. None of these

Discussion

1147.	In an ideal mixed reactor (at steady state), the
A.	Space time is equivalent to holding time for constant density systems
B.	Composition throughout the reactor remains same
C.	Exit stream has the same composition as the fluid within the reactor
D.	All (A), (B) and (C)
Answer» E.

Discussion

1148.	The single parameter model proposed for describing non-ideal flow is the __________ model.
A.	Tank in series
B.	Dispersion
C.	Both (A) & (B)
D.	Neither (A) nor (B)
Answer» D. Neither (A) nor (B)

Discussion

1149.	The importance of diffusion in a catalyst are increased by
A.	Large catalyst particle size
B.	An active surface of the catalyst
C.	Small pore diameter
D.	All (A), (B) and (C)
Answer» E.

Discussion

1150.	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.
A.	1
B.	3
C.	1/3
D.	32
Answer» C. 1/3

Discussion

Explore topic-wise MCQs in Chemical Engineering.

In flow reactors, the performance equations interrelate the rate of reaction to the

A multiple reaction may be classified as a __________ reaction.

When all the limiting reactant is consumed in the reaction, the operational yield __________ the relative yield.

Molecularity of a reaction

Which of the following is an independent variable for a batch tank reactor with uniform concentration and temperature?

A balanced chemical reaction equation conforms to the law of

Enzymes (a protein) are catalysts found in organisms. Its efficiency of catalysing a reaction is due to its capacity to lower the activation energy of the reaction. The enzyme ptyalin used for food digestion is present in

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

A reaction in which one of the products of reaction acts as a catalyst is called a/an __________ reaction.

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

When the density of the reaction mixture is constant in a chemical reaction, the ratio of the mean residence time to space time is

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

The rate of a chemical reaction is almost doubled for every 10°C rise in temperature. The rate will increase __________ times, if the temperature rises from 10 to 100°C.

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

An autothermal reactor is

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

Sulphuric acid is used as a catalyst in the

A trickle bed reactor is the one, which

In a chemical reaction, __________ are conserved.

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

With decrease in temperature, the equilibrium conversion of a reversible endothermic reaction

The energy balance equation over a tubular reactor under transient conditions is

Ionic reactions occur in

Exothermic reactions are best carried out in

N' plug flow reactors in series with a total volume 'V' gives the same conversion as a single plug flow reactor of volume 'V' for __________ order reactions.

The experimentally determined overall order of the reaction, A + B → C + D, is two. Then the

Enzymes are destroyed, when the

Backmixing is most predominant in

________ is the response curve for a step input signal from a reactor

For the chemical reaction X → Y, it is observed that, on doubling the concentration of 'X', the reaction rate quadruples. If the reaction rate is proportional to Cx n , then what is the value of „n‟?

An imbalanced chemical reaction equation is against the law of

For a zero order chemical reaction, the

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

Which of the following is a controlling factor in very fast heterogeneous reaction?

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.

In case of physical adsorption, the heat of adsorption is of the order of __________ kcal/kg.mole.

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

In the reversible reaction of the type, A + B ⇌ AB, in general

The knowledge of initial concentration and rate constant is necessary to determine the half life time of a reaction of __________ order.

For a solid catalysed chemical reaction, the effectiveness of solid catalyst depends upon the __________ adsorption.

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

A backmix reactor

Carbon particles accumulated on the catalyst used in the gas oil cracking lies in the category of __________ poison.

A batch reactor is suitable for

For an ideal plug flow reactor, the value of Peclet number is

Photochemical reaction rate does not depend significantly on temperature, because

In an ideal mixed reactor (at steady state), the

The single parameter model proposed for describing non-ideal flow is the __________ model.

The importance of diffusion in a catalyst are increased by

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.