The reaction rate almost gets doubled for 10°C rise in temperature. This is due to the fact that the

increased temperature reduces the activation energy.

fraction of molecules having threshold energy increases.

value of threshold energy decreases.

A spherical porous catalyst particle of radius R is subjected to reactant A which reacts to form B by a zero order surface reaction . 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 can not be 7/8 as it must always be 1.

'Unreacted core model' represents the reaction involving

manufacture of carbon disulphide from elements.

For all positive reaction orders for a particular duty,

ratio of the volume of the mixed reactor to that of the plug-flow reactor decreases with order.

mixed reactor is always larger than the plug-flow reactor.

ratio of the volume of the mixed reactor to that of the plug-flow reactor decreases with order.

reactor size is independent of the type of flow.

density variation during reaction affects design.

For reactions in parallel viz (desired product) and (unwanted product), if the order of the desired reaction is higher than that of the undesired reaction, a

single CSTR is the most suitable.

batch reactor is preferred over a single CSTR for high yield.

tubular reactor is preferred over a single CSTR for high yield.

single CSTR is the most suitable.

A batch reactor is characterised by

variation in extent of reaction and properties of the reaction mixture with time.

The 'E' curve for a non-ideal reactor defines the fraction of fluid having age between and +

averaged over the inlet and outlet

A chemical reaction, 3, is conducted in a constant pressure vessel. Starting with pure , the volume of the reaction mixture increases 3 times in 6 minutes. The fractional conversion is

data insufficient, can't be predicted

In the reversible reaction of the type, + , 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 en-dothermic.

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.

On application of pressure to the equilibrium system, ice water ; which of the following phenomenon will occur ?

Equilibrium will not be attained

With the same reaction time, initial concentration and feed rate, the reaction 2 is carried out separately in CSTR and P.F. reactor of equal volumes. The conversion will be

data insufficient; can't be predicted

The irreversible reaction, , is the special case of the reversible reaction, , in which the

equilibrium constant is infinite.

fractional conversion of 'A' at equilibrium is unity.

concentration of 'A' at equilibrium is zero.

1443 + Mcqs in Chemical Reaction Engineering in Chemical Engineering Page 2 McqOptions

51.	A second order reaction of the form + is called a pseudo-first order reaction, when
A.	=
B.	>
C.	>
D.	≥
Answer» E.

Discussion

52.	In case of unimolecular type elementary reaction, , plug flow reactor as compared to mixed reactor is
A.	more
B.	same
C.	less
D.	unpredictable
Answer» B. same

Discussion

53.	What is the value of '' if the reaction rate of the chemical reaction , is proportional to and it is found that the reaction rate triples, when the concentration of '' is increased 9 times ?
A.	1/2
B.	1/3
C.	1/9
D.	3
Answer» B. 1/3

Discussion

54.	The following half life data are available for the irreversible liquid phase reaction products.The overall order of reaction is
A.	0.5
B.	1
C.	1.5
D.	2
Answer» D. 2

Discussion

55.	A non-catalytic chemical reaction of the type is called a __________ reaction.
A.	parallel
B.	series
C.	series-parallel
D.	none of these
Answer» D. none of these

Discussion

56.	For the reaction, + 2 + ,
A.	=
B.	= -
C.	= 2
D.	=
E.	/2
Answer» C. = 2

Discussion

57.	The exit age distribution curve E(t) for an ideal CSTR with the average residence time, τ, is given by
A.	e
B.	1 - e
Answer» C.

Discussion

58.	A batch adiabatic reactor at an initial temperature of 373°K is being used for the reaction, . Assume the heat of reaction is - 1kJ/mole at 373°K and heat capacity of both and to be constant and equal to 50J/mole.K. The temperature rise after a conversion of 0.5 will be
A.	5°C
B.	10°C
C.	20°C
D.	100°C
Answer» C. 20°C

Discussion

59.	The fractional volume change between no conversion and complete conversion, for the isothermal gas phase reaction, 2 , is
A.	0.5
B.	-0.5
C.	1
D.	1.5
Answer» C. 1

Discussion

60.	For the liquid phase zero order irreversible reaction , the conversion of A in a CSTR is found to be 0.3 at a space velocity of 0.1min . What will be the conversion for a PFR with a space velocity of 0.2 min? Assume that all the other operating conditions are the same for CSTR and PFR.
A.	0.15
B.	0.30
C.	0.60
D.	0.90
Answer» D. 0.90

Discussion

61.	For the chemical reaction , it is found that the rate of reaction doubles as the concentration of '' is doubled. If the reaction rate is proportional to , then what is the value of '' for this chemical reaction ?
A.	1
B.	2
C.	3
D.	0
Answer» B. 2

Discussion

62.	The reaction rate almost gets doubled for 10°C rise in temperature. This is due to the fact that the
A.	increased temperature reduces the activation energy.
B.	fraction of molecules having threshold energy increases.
C.	collision frequency increases.
D.	value of threshold energy decreases.
Answer» C. collision frequency increases.

Discussion

63.	The reaction is conducted in an adiabatic plug flow reactor (PFR). Pure A at a concentration of 2 kmol/m is fed to the reactor at the rate of 0.01 m /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 = = 100kJ/kmole. K (may be assumed to be independent of temperature))
A.	400
B.	500
C.	600
D.	1000
Answer» D. 1000

Discussion

64.	A first order homogeneous reaction of the type (consecutive reaction) is carried out in a CSTR. Which of the following curves respectively show the variation of the concentration of , and with time?
A.	I, II, III
B.	III, II, I
C.	III, I, II
D.	II, III, i
Answer» C. III, I, II

Discussion

65.	Most important characteristics of gas-liquid reactors are the
A.	specific inter-facial area
B.	liquid hold-up
C.	both (a) and (b)
D.	none of these
Answer» D. none of these

Discussion

66.	Second order consecutive irreversible reactions were carried out in a constant volume isothermal batch reactor with different initial feed compositions. Reactor temperature was same in all the cases. In experiments where the ratio of concentration of to that of in the initial feed was less than 0.5, the concentration of increased first, reached a maximum and then declined with time. However, for all experiments where this concentration ratio was 0.5 or above, concentration of B decreased monotonically with time right from the beginning. What is the ratio of the two rate constants (/)?
A.	1/4
B.	1/2
C.	2
D.	4
Answer» B. 1/2

Discussion

67.	A spherical porous catalyst particle of radius R is subjected to reactant A which reacts to form B by a zero order surface reaction . 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 can not be 7/8 as it must always be 1.
Answer» B. Inner catalyst core of radius R/2 does not participate in reaction.

Discussion

68.	Given, 3H + CO = CH + HO, = 10 and, 4H + CO = CH + 2HO, = 10the for the reaction CO + HO = CO + H is
A.	10
B.	10
C.	10
D.	l0
Answer» E.

Discussion

69.	The reaction is conducted in an isothermal batch reactor. If the conversion of A increases linearly with holding time, then the order of the reaction is
A.	0
B.	1
C.	1.5
D.	2
Answer» B. 1

Discussion

70.	'Unreacted core model' represents the reaction involving
A.	combustion of coal particles.
B.	roasting of sulphide ores.
C.	manufacture of carbon disulphide from elements.
D.	none of these.
Answer» C. manufacture of carbon disulphide from elements.

Discussion

71.	Pure A in gas phase enters a reactor 50% of this A is converted to B through the reaction, 3. Mole fraction of A in the exit stream is
A.	1/2
B.	1/3
C.	1/4
D.	1/5
Answer» C. 1/4

Discussion

72.	For all positive reaction orders for a particular duty,
A.	mixed reactor is always larger than the plug-flow reactor.
B.	ratio of the volume of the mixed reactor to that of the plug-flow reactor decreases with order.
C.	reactor size is independent of the type of flow.
D.	density variation during reaction affects design.
Answer» B. ratio of the volume of the mixed reactor to that of the plug-flow reactor decreases with order.

Discussion

73.	The value of steric factor 'P' in the equation = e usually ranges from
A.	l.0 to 10
B.	l.l.to 10
C.	0.1 to 0.9
D.	none of these
Answer» B. l.l.to 10

Discussion

74.	The exit age distribution of a fluid leaving a vessel (denoted by E) is used to study the extent of non-ideal flow in the vessel. The value of is
A.	0
B.	1
C.	∞
D.	π
Answer» C. ∞

Discussion

75.	Three plug flow reactors (PFR's) of 4, 5 & 6 m volumes are arranged in two branches as shown below in the figure.If the total feed rate is 300 tons/hr, then for the same conversion in each branch, the feed rate through branch II should be __________ tons/hr.
A.	100
B.	150
C.	200
D.	225
Answer» B. 150

Discussion

76.	In a chemical reaction , it is observed that the (i) rate of formation of '' is doubled on doubling the concentration of ''. (ii) rate of formation of '' is quadrupled on doubling the concentration of ''. (iii) doubling the concentration of '' does not affect the rate of formation of ''. What is the order of the above chemical reaction?
A.	Zeroth order
B.	First order
C.	Second order
D.	Third order
Answer» E.

Discussion

77.	The half life period of a first order reaction is given by (where, = rate constant. )
A.	1.5
B.	2.5
C.	0.693/
D.	6.93
Answer» D. 6.93

Discussion

78.	For reactions in parallel viz (desired product) and (unwanted product), if the order of the desired reaction is higher than that of the undesired reaction, a
A.	batch reactor is preferred over a single CSTR for high yield.
B.	tubular reactor is preferred over a single CSTR for high yield.
C.	both (a) and (b).
D.	single CSTR is the most suitable.
Answer» D. single CSTR is the most suitable.

Discussion

79.	For a gaseous phase reaction, rate of reaction is equal to . . . If the volume of the reactor is suddenly reduced to l/4th of its initial volume, then the rate of reaction compared to the original rate will be __________ times.
A.	8
B.	16
C.	1/8
D.	1/16
Answer» C. 1/8

Discussion

80.	The effect of increasing pressure on the gaseous equilibrium of the reaction 2+3 3+2 indicates that
A.	pressure has no effect.
B.	backward reaction is favoured.
C.	forward reaction is favoured.
D.	none of these.
Answer» B. backward reaction is favoured.

Discussion

81.	If in the gaseous phase reaction, NO 2NO, x is the part of NO which dissociates, then the number of molecules at equilibrium will be
A.	(1 + x)
B.	(1 - x)
C.	(1 + x)
D.	(1 - x)
Answer» B. (1 - x)

Discussion

82.	A batch reactor is characterised by
A.	constant residence time.
B.	variation in extent of reaction and properties of the reaction mixture with time.
C.	variation in reactor volume.
D.	very low conversion.
Answer» C. variation in reactor volume.

Discussion

83.	The 'E' curve for a non-ideal reactor defines the fraction of fluid having age between and +
A.	at the inlet
B.	at the outlet
C.	in the reactor
D.	averaged over the inlet and outlet
Answer» C. in the reactor

Discussion

84.	A chemical reaction, 3, is conducted in a constant pressure vessel. Starting with pure , the volume of the reaction mixture increases 3 times in 6 minutes. The fractional conversion is
A.	0.33
B.	0.5
C.	1
D.	data insufficient, can't be predicted
Answer» D. data insufficient, can't be predicted

Discussion

85.	A CSTR is to be designed in which an exothermic liquid phase first order reaction of the type, , is taking place. The reactor is to be provided with a jacket in which coolant is flowing. Following data is given: = 5 kmole/m ; = 0.5; Feed temperature = reactor temperature = 40°C. Rate constant at 40°C = 1 min ; (Δ) = - 40kJ/mole; ρ = 1000kg/m = 4 J/gm.°C ; = 10 m/min (ρ and are same for the reactant and product streams). The amount of heat to be removed is
A.	2/3 kW
B.	1kW
C.	5/3 kW
D.	4kW
Answer» D. 4kW

Discussion

86.	The rate of the reaction, , quadruples when the concentration of '' is doubled. The rate expression for the reaction is, = , the value of '' in this case will be
A.	0
B.	1
C.	2
D.	3
Answer» D. 3

Discussion

87.	What is the Thiele modulus of the solid catalysed first order reaction, , if the pore diffusion offers negligible resistance to reaction ?
A.	< 5
B.	< 0.5
C.	> 1
D.	5
Answer» C. > 1

Discussion

88.	In the reversible reaction of the type, + , in general
A.	both forward and backward reactions will be exothermic.
B.	neither of the reactions will be en-dothermic.
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

89.	For an isothermal second order aqueous phase reaction, , the ratio of the time required for 90% conversion to the time required for 45% conversion is
A.	2
B.	4
C.	11
D.	22
Answer» D. 22

Discussion

90.	The use of space time is preferred over the mean residence time in the design of a/an
A.	batch reactor
B.	ideal tubular-flow reactor
C.	slurry reactor
D.	CSTR
Answer» C. slurry reactor

Discussion

91.	A pulse tracer is introduced in an ideal CSTR (with a mean residence time ι) at time, t = 0. The time taken for the exit concentration of the tracer to reach half of its initial value will be
A.	2τ
B.	0.5τ
C.	τ/0.693
D.	0.693τ
Answer» B. 0.5τ

Discussion

92.	On application of pressure to the equilibrium system, ice water ; which of the following phenomenon will occur ?
A.	Water will evaporate
B.	Equilibrium will not be attained
C.	More ice will be formed
D.	More water will be formed.
Answer» E.

Discussion

93.	The value of '' for a chemical reaction A B, whose reaction rate is , will be __________ if the rate of the reaction increases by a factor of 8, when the concentration of is doubled.
A.	0
B.	1
C.	2
D.	3
Answer» E.

Discussion

94.	'' number of plug flow reactors (P.F.R) in series with a total volume '' gives the same conversion as one P.F.R. of volume
A.	/
B.	.
C.	1/
Answer» C. 1/

Discussion

95.	The gas phase reaction 2 is carried out in an isothermal plug flow reactor. The feed consists of 80 mole % A and 20 mole % inerts. If the conversion of at the reactor exit is 50%, then / at the outlet of the reactor is
A.	2/3
B.	5/8
C.	1/3
D.	3/8
Answer» C. 1/3

Discussion

96.	With the same reaction time, initial concentration and feed rate, the reaction 2 is carried out separately in CSTR and P.F. reactor of equal volumes. The conversion will be
A.	higher in P.F. reactor
B.	higher in CSTR
C.	same in both the reactors
D.	data insufficient; can't be predicted
Answer» B. higher in CSTR

Discussion

97.	The following gas phase reactions are carried out isothermally in a CSTR. 2 ; = ; = 20mole/(sec.m bar) 3 ; = ; = 40mole/(sec.m .bar)What is the maximum possible value of (mole/sec.) ?
A.	1/3
B.	1/2
C.	2/3
D.	2
Answer» D. 2

Discussion

98.	Half life period of a chemical reaction is proportional to , if the reaction is of __________ order.
A.	first
B.	zero
C.	second
D.	third
Answer» D. third

Discussion

99.	The irreversible reaction, , is the special case of the reversible reaction, , in which the
A.	equilibrium constant is infinite.
B.	fractional conversion of 'A' at equilibrium is unity.
C.	concentration of 'A' at equilibrium is zero.
D.	all (a), (b) and (c).
Answer» E.

Discussion

100.	For identical flow rate, feed composition and for elementary first order reactions, '' equal sized mixed reactors in series with a total volume '' gives the same conversion as a single plug flow reactor of volume '' for constant density systems. This is true, when the value of '' is
A.	1
B.	>1
C.	∞
D.	≥1
Answer» D. ≥1

Discussion

Explore topic-wise MCQs in Chemical Engineering.

A second order reaction of the form + is called a pseudo-first order reaction, when

In case of unimolecular type elementary reaction, , plug flow reactor as compared to mixed reactor is

What is the value of '' if the reaction rate of the chemical reaction , is proportional to and it is found that the reaction rate triples, when the concentration of '' is increased 9 times ?

The following half life data are available for the irreversible liquid phase reaction products.The overall order of reaction is

A non-catalytic chemical reaction of the type is called a __________ reaction.

For the reaction, + 2 + ,

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

A batch adiabatic reactor at an initial temperature of 373°K is being used for the reaction, . Assume the heat of reaction is - 1kJ/mole at 373°K and heat capacity of both and to be constant and equal to 50J/mole.K. The temperature rise after a conversion of 0.5 will be

The fractional volume change between no conversion and complete conversion, for the isothermal gas phase reaction, 2 , is

For the liquid phase zero order irreversible reaction , the conversion of A in a CSTR is found to be 0.3 at a space velocity of 0.1min . What will be the conversion for a PFR with a space velocity of 0.2 min? Assume that all the other operating conditions are the same for CSTR and PFR.

For the chemical reaction , it is found that the rate of reaction doubles as the concentration of '' is doubled. If the reaction rate is proportional to , then what is the value of '' for this chemical reaction ?

The reaction rate almost gets doubled for 10°C rise in temperature. This is due to the fact that the

A first order homogeneous reaction of the type (consecutive reaction) is carried out in a CSTR. Which of the following curves respectively show the variation of the concentration of , and with time?

Most important characteristics of gas-liquid reactors are the

Given, 3H + CO = CH + HO, = 10 and, 4H + CO = CH + 2HO, = 10the for the reaction CO + HO = CO + H is

The reaction is conducted in an isothermal batch reactor. If the conversion of A increases linearly with holding time, then the order of the reaction is

'Unreacted core model' represents the reaction involving

Pure A in gas phase enters a reactor 50% of this A is converted to B through the reaction, 3. Mole fraction of A in the exit stream is

For all positive reaction orders for a particular duty,

The value of steric factor 'P' in the equation = e usually ranges from

The exit age distribution of a fluid leaving a vessel (denoted by E) is used to study the extent of non-ideal flow in the vessel. The value of is

Three plug flow reactors (PFR's) of 4, 5 & 6 m volumes are arranged in two branches as shown below in the figure.If the total feed rate is 300 tons/hr, then for the same conversion in each branch, the feed rate through branch II should be __________ tons/hr.

The half life period of a first order reaction is given by (where, = rate constant. )

For reactions in parallel viz (desired product) and (unwanted product), if the order of the desired reaction is higher than that of the undesired reaction, a

For a gaseous phase reaction, rate of reaction is equal to . . . If the volume of the reactor is suddenly reduced to l/4th of its initial volume, then the rate of reaction compared to the original rate will be __________ times.

The effect of increasing pressure on the gaseous equilibrium of the reaction 2+3 3+2 indicates that

If in the gaseous phase reaction, NO 2NO, x is the part of NO which dissociates, then the number of molecules at equilibrium will be

A batch reactor is characterised by

The 'E' curve for a non-ideal reactor defines the fraction of fluid having age between and +

A chemical reaction, 3, is conducted in a constant pressure vessel. Starting with pure , the volume of the reaction mixture increases 3 times in 6 minutes. The fractional conversion is

The rate of the reaction, , quadruples when the concentration of '' is doubled. The rate expression for the reaction is, = , the value of '' in this case will be

What is the Thiele modulus of the solid catalysed first order reaction, , if the pore diffusion offers negligible resistance to reaction ?

In the reversible reaction of the type, + , in general

For an isothermal second order aqueous phase reaction, , the ratio of the time required for 90% conversion to the time required for 45% conversion is

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

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

On application of pressure to the equilibrium system, ice water ; which of the following phenomenon will occur ?

The value of '' for a chemical reaction A B, whose reaction rate is , will be __________ if the rate of the reaction increases by a factor of 8, when the concentration of is doubled.

'' number of plug flow reactors (P.F.R) in series with a total volume '' gives the same conversion as one P.F.R. of volume

The gas phase reaction 2 is carried out in an isothermal plug flow reactor. The feed consists of 80 mole % A and 20 mole % inerts. If the conversion of at the reactor exit is 50%, then / at the outlet of the reactor is

With the same reaction time, initial concentration and feed rate, the reaction 2 is carried out separately in CSTR and P.F. reactor of equal volumes. The conversion will be

The following gas phase reactions are carried out isothermally in a CSTR. 2 ; = ; = 20mole/(sec.m bar) 3 ; = ; = 40mole/(sec.m .bar)What is the maximum possible value of (mole/sec.) ?

Half life period of a chemical reaction is proportional to , if the reaction is of __________ order.

The irreversible reaction, , is the special case of the reversible reaction, , in which the

For identical flow rate, feed composition and for elementary first order reactions, '' equal sized mixed reactors in series with a total volume '' gives the same conversion as a single plug flow reactor of volume '' for constant density systems. This is true, when the value of '' is