Velocity of a reaction depends upon the

Temperature at which the reaction is carried

Chemical reaction rate of a component depends upon the

Composition of the component only

A spherical porous catalyst particle of radius R is subjected to reactant A which reacts to form B by a zero order surface reaction A → B. Film mass transfer resistance is negligible and pore diffusion of A is rate controlling. The effectiveness factor of the catalyst is reported as 7/8. Which of the following statement is true?

Inner catalyst core of radius R/2 does not participate in reaction

Inner catalyst core of radius R/8 does not participate in reaction

Inner catalyst core of radius R/2 does not participate in reaction

Inner catalyst core of radius 7R/8 does not participate in reaction

Effectiveness factor for a zero order reaction cannot be 7/8 as it must always be 1

Specific rate constant for a second order reaction

Depends on the nature of the reactants

A space time of 3 hours for a flow reactor means that

Three reactor volumes of feed can be processed every hour

The time required to process one reactor volume of feed (measured at specified conditions) is 3 hours

Three reactor volumes of feed can be processed every hour

It takes three hours to dump the entire volume of the reactor with feed

Conversion is cent per cent after three hours

A reactor is generally termed as an autoclave, when it is a

Atmospheric pressure tank reactor

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

Reaction kinetics for single particle

Size distribution of solids being treated

Flow patterns of solids and fluid in the reactor

Rate of a chemical reaction is not influenced by the

Number of molecules of reactants taking part in a reaction

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

Conversion of the reactant at equilibrium condition is zero

Reactant concentration at equilibrium condition is zero

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

Distribution of reaction products

A catalyst is said to be a negative catalyst, if it

Reduces the value of equilibrium constant

A back mix reactor is

Suitable for gas phase reactions

Same as plug flow reactor (PFR)

Same as ideal stirred tank reactor

The increase in the rate of reaction with temperature is due to

Increase in the average kinetic energy of the reacting molecules

Increase in the number of effective collisions

Increase in the average kinetic energy of the reacting molecules

Pick out the wrong statement.

Equilibrium concentrations in enzyme catalysed reactions can be calculated by using the thermodynamic properties of substrates & products

Catalytic activity of enzyme catalysed reactions which is affected by temperature, pH value & chemical agents, is maximum at a temperature of about 45°C

Most of the enzyme catalysed reactions involve at least two substrates

Enzymes help in increasing the activation energy of the reaction

Equilibrium concentrations in enzyme catalysed reactions can be calculated by using the thermodynamic properties of substrates & products

For an ideal gas mixture undergoing a reversible gaseous phase chemical reaction, the equilibrium constant

Increases /decreases with pressure depending on the stoichiometric co-efficients of the reaction

Half life period of a chemical reaction is

Half of the space time of a reaction

The time required to reduce the concentration of the reacting substance to half its initial value

Half of the space time of a reaction

Half of the residence time of a reaction

A space velocity of 5 hr-1 means that

After every 5 hours, reactor is being filled with the feed

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

After every 5 hours, reactor is being filled with the feed

Cent per cent conversion can be achieved in at least 5 hours

A fixed conversion of a given batch of feed takes 5 hours

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

Is different than that in the reactor

Depends upon the flow rate of inlet stream

Pick out the wrong statement pertaining to space velocity of flow reactors.

The unit of space velocity is (time)-1

The space velocity of 3 hr-1 means that three reactor volumes of feed at specified conditions are being fed into the reactor every hour

The space velocity of 3 hr-1 means that one third reactor volume of feed at specified conditions are being fed into the reactor

In Langmuir treatment of adsorption,

All the adsorption does not take place by the same mechanism

Whole surface of the catalyst does not have the same activity for adsorption and there is attraction between the adsorbed molecule

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

All the adsorption does not take place by the same mechanism

Extent of adsorption is more than one complete monomolecular layer on the surface

Which of the following resistances is not involved in a gas phase catalytic (gas-solid) reaction?

Gas film and pore surface diffusion resistances for reactants

Gas film and pore surface diffusion resistances for products

The minimum energy required to allow a chemical reaction to proceed is termed as the 'threshold energy '. Chemical reactions with low activation energy are:

Insensitive to temperature changes

Fluidised bed reactor is characterised by

Comparatively smaller equipment

Absence of continuous catalyst regeneration facility

A first order irreversible reaction, A → B is carried out separately in a constant volume as well as in a variable volume reactor for a particular period. It signifies that __________ in the two reactors.

Both the conversion as well as concentrations will be different

Both conversion as well as concentration are same

Conversion in both will be the same but concentrations will be different

Both the conversion as well as concentrations will be different

1443 + Mcqs in Chemical Reaction Engineering in Chemical Engineering Page 25 McqOptions

1201.	From among the following, choose one which is not an exothermic process.
A.	Methanol synthesis
B.	Catalytic cracking
C.	Ammonia synthesis
D.	Oxidation of sulphur
Answer» C. Ammonia synthesis

Discussion

1202.	The ratio of moles of a reactant converted into the desired product to that converted into unwanted product is called
A.	Operational yield
B.	Relative yield
C.	Selectivity
D.	None of these
Answer» D. None of these

Discussion

1203.	Velocity of a reaction depends upon the
A.	Nature of the reactants
B.	Concentration of the reactants
C.	Temperature at which the reaction is carried
D.	All (A), (B) and (C)
Answer» E.

Discussion

1204.	If the time required to complete a definite fraction of reaction varies inversely as the concentration of the reactants, then the order of reaction is
A.	1
B.	2
C.	3
D.	4
Answer» C. 3

Discussion

1205.	Chemical reaction rate of a component depends upon the
A.	Composition of the component only
B.	Temperature of the system
C.	Pressure of the system
D.	All (A), (B) and (C)
Answer» E.

Discussion

1206.	A spherical porous catalyst particle of radius R is subjected to reactant A which reacts to form B by a zero order surface reaction A → B. Film mass transfer resistance is negligible and pore diffusion of A is rate controlling. The effectiveness factor of the catalyst is reported as 7/8. Which of the following statement is true?
A.	Inner catalyst core of radius R/8 does not participate in reaction
B.	Inner catalyst core of radius R/2 does not participate in reaction
C.	Inner catalyst core of radius 7R/8 does not participate in reaction
D.	Effectiveness factor for a zero order reaction cannot be 7/8 as it must always be 1
Answer» B. Inner catalyst core of radius R/2 does not participate in reaction

Discussion

1207.	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 Chatelier's principle).
A.	Decreases
B.	Increases
C.	Remains unaltered
D.	Changes unpredictably
Answer» B. Increases

Discussion

1208.	Specific rate constant for a second order reaction
A.	Is independent of temperature
B.	Varies with temperature
C.	Depends on the nature of the reactants
D.	Both (B) and (C)
Answer» E.

Discussion

1209.	For a first order reaction carried out in a plug flow reactor, the space time is
A.	(1/k) ln C0/C
B.	(1/k) ln C/C0
C.	k ln C0/C
D.	k ln C/C0
Answer» B. (1/k) ln C/C0

Discussion

1210.	A space time of 3 hours for a flow reactor means that
A.	The time required to process one reactor volume of feed (measured at specified conditions) is 3 hours
B.	Three reactor volumes of feed can be processed every hour
C.	It takes three hours to dump the entire volume of the reactor with feed
D.	Conversion is cent per cent after three hours
Answer» B. Three reactor volumes of feed can be processed every hour

Discussion

1211.	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.	t ∝ 1/a n
B.	t ∝ 1/a n - 1
C.	t ∝ 1/a n + 1
D.	t ∝ a n
Answer» C. t ∝ 1/a n + 1

Discussion

1212.	A reactor is generally termed as an autoclave, when it is a
A.	High pressure batch reactor
B.	Atmospheric pressure tank reactor
C.	High pressure tubular reactor
D.	Atmospheric pressure CSTR
Answer» B. Atmospheric pressure tank reactor

Discussion

1213.	For an autocatalytic reactor, the suitable reactor set up is
A.	P.F. reactors in series
B.	CSTR in series
C.	CSTR followed by P.F. reactor
D.	P.F. reactor followed by CSTR
Answer» D. P.F. reactor followed by CSTR

Discussion

1214.	Which of the following factors control the design of a fluid-solid reactor?
A.	Reaction kinetics for single particle
B.	Size distribution of solids being treated
C.	Flow patterns of solids and fluid in the reactor
D.	All (A), (B) and (C)
Answer» E.

Discussion

1215.	__________ explains the mechanism of catalysis.
A.	Activated complex theory
B.	Collision theory
C.	Thermodynamics
D.	None of these
Answer» B. Collision theory

Discussion

1216.	If Thiele modulus is __________, then the pore diffusion resistance in a catalyst may be considered as negligible.
A.	0
B.	∞
C.	< 0.5
D.	> 0.5
Answer» D. > 0.5

Discussion

1217.	Rate of a chemical reaction is not influenced by the
A.	Catalyst
B.	Temperature
C.	Reactants concentration
D.	Number of molecules of reactants taking part in a reaction
Answer» E.

Discussion

1218.	The irreversible reaction is a special case of reversible reaction, if the
A.	Equilibrium constant is 1
B.	Conversion of the reactant at equilibrium condition is zero
C.	Reactant concentration at equilibrium condition is zero
D.	All (A), (B) and (C)
Answer» D. All (A), (B) and (C)

Discussion

1219.	For multiple reactions, the flow pattern within the vessel affects the
A.	Size requirement
B.	Distribution of reaction products
C.	Both (A) and (B)
D.	Neither (A) nor (B)
Answer» D. Neither (A) nor (B)

Discussion

1220.	A catalyst is said to be a negative catalyst, if it
A.	Retards the rate of reaction
B.	Reduces the value of equilibrium constant
C.	Does not initiate the reaction
D.	All (A), (B) and (C)
Answer» B. Reduces the value of equilibrium constant

Discussion

1221.	The excess energy of reactants in a chemical reaction required to dissociate into products is termed as the __________ energy.
A.	Activation
B.	Potential
C.	Binding
D.	Threshold
Answer» B. Potential

Discussion

1222.	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
A.	m
B.	1/m
C.	√m
D.	m 2
Answer» C. √m

Discussion

1223.	If the time required to change the concentration of reactant to half its original value is independent of the initial concentration, the order of reaction is:
A.	Zero
B.	One
C.	Two
D.	Three
Answer» C. Two

Discussion

1224.	Rate constant 'k' and absolute temperature 'T' are related by collision theory (for bimolecular) as
A.	k ∝ T 1.5
B.	k ∝ exp(-E/RT)
C.	k ∝ √T
D.	k ∝ T
Answer» D. k ∝ T

Discussion

1225.	A back mix reactor is
A.	Suitable for gas phase reactions
B.	Ideal at very low conversion
C.	Same as plug flow reactor (PFR)
D.	Same as ideal stirred tank reactor
Answer» E.

Discussion

1226.	Which of the following is a characteristic of an ideal plug flow reactor?
A.	Axial dispersion
B.	Flat velocity profile
C.	Uniform mixing
D.	None of these
Answer» C. Uniform mixing

Discussion

1227.	The increase in the rate of reaction with temperature is due to
A.	Increase in the number of effective collisions
B.	Decrease in activation energy
C.	Increase in the average kinetic energy of the reacting molecules
D.	None of these
Answer» C. Increase in the average kinetic energy of the reacting molecules

Discussion

1228.	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?
A.	0
B.	1
C.	2
D.	3
Answer» B. 1

Discussion

1229.	Pick out the wrong statement.
A.	Catalytic activity of enzyme catalysed reactions which is affected by temperature, pH value & chemical agents, is maximum at a temperature of about 45°C
B.	Most of the enzyme catalysed reactions involve at least two substrates
C.	Enzymes help in increasing the activation energy of the reaction
D.	Equilibrium concentrations in enzyme catalysed reactions can be calculated by using the thermodynamic properties of substrates & products
Answer» D. Equilibrium concentrations in enzyme catalysed reactions can be calculated by using the thermodynamic properties of substrates & products

Discussion

1230.	Helium-mercury method can be used to determine the __________ of the catalyst particle
A.	Pore volume
B.	Solid density
C.	Porosity
D.	All (A), (B), & (C)
Answer» E.

Discussion

1231.	For an ideal gas mixture undergoing a reversible gaseous phase chemical reaction, the equilibrium constant
A.	Is independent of pressure
B.	Increases with pressure
C.	Decreases with pressure
D.	Increases /decreases with pressure depending on the stoichiometric co-efficients of the reaction
Answer» C. Decreases with pressure

Discussion

1232.	Which of the following is the most suitable for very high pressure gas phase reaction?
A.	Batch reactor
B.	Tubular flow reactor
C.	Stirred tank reactor
D.	Fluidised bed reactor
Answer» C. Stirred tank reactor

Discussion

1233.	Maximum equilibrium conversion for endothermic reaction is obtained at the __________ temperature.
A.	Highest possible
B.	Lowest possible
C.	Intermediate
D.	Room
Answer» B. Lowest possible

Discussion

1234.	Half life period of a chemical reaction is
A.	The time required to reduce the concentration of the reacting substance to half its initial value
B.	Half of the space time of a reaction
C.	Half of the residence time of a reaction
D.	None of these
Answer» B. Half of the space time of a reaction

Discussion

1235.	A space velocity of 5 hr-1 means that
A.	Five reactor volumes of feed (at specified conditions) are being fed into the reactor per hour
B.	After every 5 hours, reactor is being filled with the feed
C.	Cent per cent conversion can be achieved in at least 5 hours
D.	A fixed conversion of a given batch of feed takes 5 hours
Answer» B. After every 5 hours, reactor is being filled with the feed

Discussion

1236.	In a continuous flow stirred tank reactor, the composition of the exit stream
A.	Is same as that in the reactor
B.	Is different than that in the reactor
C.	Depends upon the flow rate of inlet stream
D.	None of these
Answer» B. Is different than that in the reactor

Discussion

1237.	The reaction A → B is conducted in an adiabatic plug flow reactor (PFR). Pure A at a concentration of 2 kmol/m3 is fed to the reactor at the rate of 0.01 m3 /s and at a temperature of 500 K. If the exit conversion is 20%, then the exit temperature (in k) is (Data: Heat of reaction at 298 K = - 50000 kJ/ kmole of A reacted Heat capacities CPA = CPB = 100kJ/kmole. K (may be assumed to be independent of temperature))
A.	400
B.	500
C.	600
D.	1000
Answer» D. 1000

Discussion

1238.	Kinetics of a catalytic reaction can be best studied on a/an __________ reactor.
A.	Mixed
B.	Integral (plug flow)
C.	Differential (flow)
D.	Either (A), (B) and (C)
Answer» E.

Discussion

1239.	Pick out the wrong statement pertaining to space velocity of flow reactors.
A.	The unit of space velocity is (time)-1
B.	The space velocity of 3 hr-1 means that three reactor volumes of feed at specified conditions are being fed into the reactor every hour
C.	The space velocity of 3 hr-1 means that one third reactor volume of feed at specified conditions are being fed into the reactor
D.	None of these
Answer» D. None of these

Discussion

1240.	Equilibrium of a chemical reaction as viewed by kinetics is a __________ state.
A.	Dynamic steady
B.	Static steady
C.	Dynamic unsteady
D.	None of these
Answer» B. Static steady

Discussion

1241.	For the non catalytic reaction of particles with surrounding fluid, the same needed to achieve the same fractional conversion for particles of different unchanging sizes is proportional to the particle diameter, when the __________ is the controlling resistance.
A.	Film diffusion
B.	Diffusion through ash layer
C.	Chemical reaction
D.	Either (A), (B) or (C)
Answer» D. Either (A), (B) or (C)

Discussion

1242.	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 k.mole/m3 , the volume of the mixed flow reactor should be increased by a factor of:
A.	7
B.	6
C.	3
D.	7/3
Answer» B. 6

Discussion

1243.	For every 10°C rise in temperature, the rate of chemical reaction doubles. When the temperature is increased from 30 to 70°C, the rate of reaction increases __________ times.
A.	8
B.	12
C.	16
D.	32
Answer» D. 32

Discussion

1244.	In Langmuir treatment of adsorption,
A.	Whole surface of the catalyst does not have the same activity for adsorption and there is attraction between the adsorbed molecule
B.	Whole surface of the catalyst is essentially uniform and the adsorbed molecule has no effect on the rate of adsorption per site
C.	All the adsorption does not take place by the same mechanism
D.	Extent of adsorption is more than one complete monomolecular layer on the surface
Answer» C. All the adsorption does not take place by the same mechanism

Discussion

1245.	Which of the following resistances is not involved in a gas phase catalytic (gas-solid) reaction?
A.	Ash resistance
B.	Gas film and pore surface diffusion resistances for reactants
C.	Surface phenomenon resistance
D.	Gas film and pore surface diffusion resistances for products
Answer» B. Gas film and pore surface diffusion resistances for reactants

Discussion

1246.	The minimum energy required to allow a chemical reaction to proceed is termed as the 'threshold energy '. Chemical reactions with low activation energy are:
A.	Always irreversible
B.	Insensitive to temperature changes
C.	Mostly irreversible
D.	Highly temperature sensitive
Answer» C. Mostly irreversible

Discussion

1247.	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.
A.	4
B.	8
C.	12
D.	16
Answer» E.

Discussion

1248.	Threshold energy in a reaction is equal to the
A.	Activation energy
B.	Normal energy of reactants
C.	Sum of (A) & (B)
D.	Neither (A) nor (B)
Answer» D. Neither (A) nor (B)

Discussion

1249.	Fluidised bed reactor is characterised by
A.	Uniformity of temperature
B.	Comparatively smaller equipment
C.	Very small pressure drop
D.	Absence of continuous catalyst regeneration facility
Answer» B. Comparatively smaller equipment

Discussion

1250.	A first order irreversible reaction, A → B is carried out separately in a constant volume as well as in a variable volume reactor for a particular period. It signifies that __________ in the two reactors.
A.	Both conversion as well as concentration are same
B.	Conversion in both will be the same but concentrations will be different
C.	Both the conversion as well as concentrations will be different
D.	None of these
Answer» C. Both the conversion as well as concentrations will be different

Discussion

Explore topic-wise MCQs in Chemical Engineering.

From among the following, choose one which is not an exothermic process.

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

Velocity of a reaction depends upon the

If the time required to complete a definite fraction of reaction varies inversely as the concentration of the reactants, then the order of reaction is

Chemical reaction rate of a component depends upon the

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 Chatelier's principle).

Specific rate constant for a second order reaction

For a first order reaction carried out in a plug flow reactor, the space time is

A space time of 3 hours for a flow reactor means that

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 reactor is generally termed as an autoclave, when it is a

For an autocatalytic reactor, the suitable reactor set up is

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

__________ explains the mechanism of catalysis.

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

Rate of a chemical reaction is not influenced by the

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

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

A catalyst is said to be a negative catalyst, if it

The excess energy of reactants in a chemical reaction required to dissociate into products is termed as the __________ energy.

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

If the time required to change the concentration of reactant to half its original value is independent of the initial concentration, the order of reaction is:

Rate constant 'k' and absolute temperature 'T' are related by collision theory (for bimolecular) as

A back mix reactor is

Which of the following is a characteristic of an ideal plug flow reactor?

The increase in the rate of reaction with temperature is due to

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?

Pick out the wrong statement.

Helium-mercury method can be used to determine the __________ of the catalyst particle

For an ideal gas mixture undergoing a reversible gaseous phase chemical reaction, the equilibrium constant

Which of the following is the most suitable for very high pressure gas phase reaction?

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

Half life period of a chemical reaction is

A space velocity of 5 hr-1 means that

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

Kinetics of a catalytic reaction can be best studied on a/an __________ reactor.

Pick out the wrong statement pertaining to space velocity of flow reactors.

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

For the non catalytic reaction of particles with surrounding fluid, the same needed to achieve the same fractional conversion for particles of different unchanging sizes is proportional to the particle diameter, when the __________ is the controlling resistance.

For every 10°C rise in temperature, the rate of chemical reaction doubles. When the temperature is increased from 30 to 70°C, the rate of reaction increases __________ times.

In Langmuir treatment of adsorption,

Which of the following resistances is not involved in a gas phase catalytic (gas-solid) reaction?

The minimum energy required to allow a chemical reaction to proceed is termed as the 'threshold energy '. Chemical reactions with low activation energy are:

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.

Threshold energy in a reaction is equal to the

Fluidised bed reactor is characterised by

A first order irreversible reaction, A → B is carried out separately in a constant volume as well as in a variable volume reactor for a particular period. It signifies that __________ in the two reactors.