Chemical Reaction Engineering

Question 1

Which of the following will give maximum gas conversion ?
Fixed bed reactor.
Fluidised bed reactor.
Semi-fluidised bed reactor.
Plug-flow catalytic reactor.

Answer 1

Semi-fluidised bed reactor.

Combines advantages of fixed bed + fluidised bed reactors.

Question 2

__________ explains the mechanism of catalysis.
Activated complex theory
Collision theory
Thermodynamics
None of these

Answer 2

Activated complex theory

Question 3

From among the following, choose one which is not an exothermic process.
Methanol synthesis
Catalytic cracking
Ammonia synthesis
Oxidation of sulphur

Answer 3

Catalytic cracking

Question 4

The fractional volume change of the system for the isothermal gas phase reaction, A 3B , between no conversion and complete conversion is
0.5
1
2
3

Answer 4

2

Question 5

A catalyst _____.
initiates a reaction.
lowers the activation energy of reacting molecules.
is capable of reacting with any one of the reactants.
can not be recovered chemically unchanged at the end of a chemical reaction.

Answer 5

lowers the activation energy of reacting molecules.

Question 6

What is the order of a chemical reaction, A + 2B → K, if the rate of formation of ‘C’, increases by a factor of 2.82 on doubling the concentration of ‘A’ and increases by a factor of 9 on trebling the concentration of ‘B’?
7/2
7/4
5/2
5/4

Answer 6

7/2

Question 7

For high conversion in a highly exothermic solid catalysed reaction, use a __________ bed reactor.
fixed
fluidised bed reactor followed by a fixed
fixed bed reactor followed by a fluidised
fluidised

Answer 7

fluidised bed reactor followed by a fixed

Question 8

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.
8
12
16
32

Answer 8

16

Question 9

The single parameter model proposed for describing non-ideal flow is the __________ model.
tank in series
dispersion
both (a) & (b)
neither (a) nor (b).

Answer 9

both (a) & (b)

Question 10

A first order reaction requires two equal sized CSTR. The conversion is
less when they are connected in series.
more when they are connected in series.
more when they are connected in parallel.
same whether they are connected in series or in parallel.

Answer 10

more when they are connected in series.

Question 11

In case of physical adsorption, the heat of adsorption is of the order of __________ kcal/kg.mole.
100
1000
10000
100000

Answer 11

1000

Question 12

The most unsuitable reactor for carrying out reactions in which high reactant concentration favours high yields is
backmix reactor
plug flow reactor
series of CSTR
PFR in series

Answer 12

backmix reactor

Question 13

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.
none of these.

Answer 13

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

Space velocity should be feed rate.

Question 14

A reactor is generally termed as an autoclave, when it is a
high pressure batch reactor.
atmospheric pressure tank reactor.
high pressure tubular reactor.
atmospheric pressure CSTR.

Answer 14

high pressure batch reactor.

Question 15

6 gm of carbon is burnt with an amount of air containing 18 gm oxygen. The product contains 16.5 gms CO2 and 2.8 gms CO besides other constituents. What is the degree of conversion on the basis of disappearance of limiting reactant ?
100%
95%
75%
20%

Answer 15

95%

Question 16

The rate constant of a chemical reaction decreases by decreasing the
pressure
concentration of reactants
temperature
duration of reaction

Answer 16

temperature

Question 17

Reaction rate equation for the reaction, R + 2S → X = Y is -dCR/dt = KCRCS^2 . If S at is present in large excess, what is the order of this reaction?
zero
one
two
three

Answer 17

one

Question 18

Rate of a gaseous phase reaction is given by, -dpA/dt = Kp^2*A. The unit of rate constant is
(atm)-1
(hr)-1
(atm)-1.(hr)-1
atm.(hr)-1

Answer 18

(atm)-1.(hr)-1

Question 19

__________ is the response curve for a step input signal from a reactor.
S-curve
C-curve
I-curve
none of these

Answer 19

S-curve

Question 20

‘If the catalyst pore size is small in comparison with the mean free path, collisions with the pore wall controls the process’. The diffusivity under this condition is called ‘Knudsen diffusivity’, which is affected by the ____.
pressure
temperature
both (a) & (b)
neither (a) nor (b)

Answer 20

both (a) & (b)

T only. Mechanism is dependent on collision bw gas molecules.

Question 21

Which of the following is the most suitable for very high pressure gas phase reaction ?
Batch reactor
Tubular flow reactor
Stirred tank reactor
Fluidised bed reactor

Answer 21

Tubular flow reactor

Question 22

The reaction between oxygen and organic material is a/an __________ reaction.
exothermic
endothermic
biochemical
photochemical

Answer 22

exothermic

Question 23

With decrease in temperature, the equilibrium conversion of a reversible endother-mic reaction
decreases
increases
remains unaffected
increases linearly with temperature

Answer 23

decreases

Question 24

In an exothermic chemical reaction, the reactants compared to the products have
higher temperature
more energy
less energy
same energy.

Answer 24

more energy

Question 25

In a consecutive reaction system A→B→C when E1 is much greater than E2, the yield of B increases with the _____.
increase of temperature.
decrease of temperature.
increase in initial concentration of A.
decrease in initial concentration of A.

Answer 25

increase of temperature.

Question 26

A reversible liquid phase endothermic reaction is to be carried out in a plug flow reactor. For minimum reactor volume, it should be operated such that the temperature along the length
decreases.
increases.
is at the highest allowable temperature throughout.
first increases and then decreases.

Answer 26

is at the highest allowable temperature throughout.

Question 27

The rate constant of a chemical reaction increases by 100 times when the temperature is increased from 400 °K to 500 °K. Assuming transition state theory is valid, the value of E/R is
8987°K
9210°K
8764°K
8621°K

Answer 27

9210°K

Question 28

A batch reactor is suitable for
achieving cent percent conversion of reactants into products.
large scale gaseous phase reactions.
liquid phase reactions.
obtaining uniform polymerisation products in highly exothermic reactions.

Answer 28

liquid phase reactions.

Question 29

For a heterogeneous catalytic reaction
free energy of activation is lowered in the presence of catalyst, which remains unchanged at the end of reaction.
a relatively small amount of catalyst can cause the conversion of large amount of reactants which does not mean that catalyst concentration is important.
the catalyst does not form an intermediate complex with the reactant.
the surface of the catalyst does not play an important role during reaction.

Answer 29

free energy of activation is lowered in the presence of catalyst, which remains unchanged at the end of reaction.

Question 30

The increase in the rate of reaction with temperature is due to
increase in the number of effective collisions.
decrease in activation energy.
increase in the average kinetic energy of the reacting molecules.
none of these.

Answer 30

decrease in activation energy.

Question 31

A catalyst loses its activity due to
loss in surface area of the active component.
agglomeration of metal particles caused by thermal sintering of the solid surface.
covering of the catalytic active sites by a foregin substance.
all (a), (b) and (c).

Answer 31

all (a), (b) and (c).

Question 32

‘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.
first
second
third
any

Answer 32

any

Question 33

For the irreversible elementary reactions in parallel viz K2: X→Y, K1: X→Z , the rate of disappearance of ‘X’ is equal to:
CA(K1+K2)
CA(K1 + K2)/2
CA . K1/2
CA . K2/2

Answer 33

CA(K1+K2)

Question 34

For an isothermal variable volume batch reactor, the following relation is applicable for a first order irreversible reaction.
XA = k . t
(Ca0/1+𝛆AXA)(dXA/dt) = k
-ln(1 - XA) = kt
εA . ln (1 - XA) = k . t

Answer 34

(Ca0/1+𝛆AXA)(dXA/dt) = k

Question 35

For a zero order chemical reaction, the
half life period is directly proportion to the initial concentration of the reac-tants.
plot of products concentration with time is a straight line through the origin.
products concentration increases linerarly with time.
all (a), (b) and (c).

Answer 35

all (a), (b) and (c).

Question 36

BET apparatus
measures the catalyst surface area directly.
operates at very high pressure.
is made entirely of stainless steel.
none of these.

Answer 36

none of these.

does not measure SA directly, operates at low pressure, and contains glass or quartz.

Question 37

Radioactive decay follows __________ order kinetics.
first
second
third
zero.

Answer 37

first

Question 38

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

Answer 38

activation

Question 39

For a solid catalysed chemical reaction, the effectiveness of solid catalyst depends upon the __________ adsorption.
physical
chemical
both (a) and (b)
neither (a) nor (b)

Answer 39

chemical

Question 40

Pick out the correct statement.
In catalytic reactions, the catalyst reacts with the reactants.
A catalyst initiates a chemical reaction.
A catalyst lowers the activation energy of the reacting molecules.
A catalyst can not be recovered chemi cally unchanged at the end of the chemical reaction.

Answer 40

A catalyst lowers the activation energy of the reacting molecules.

Question 41

The dimensions of rate constant for reaction 3A B are (l/gm mole)/min. Therefore the reaction order is
0
1
2
3

Answer 41

2

Question 42

Pick out the correct statement
Reactions with high activation energies are very temperature sensitive.
Chemical equilibrium is a static state.
A photochemical reaction is catalysed by light.
A chemical reaction occurs when the energy of the reacting molecule is less than the activation energy of the reaction.

Answer 42

Reactions with high activation energies are very temperature sensitive.

Question 43

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
0
1
2
3

Answer 43

2

Question 44

Sulphuric acid is used as a catalyst in the
hydrogenation of oils.
gas phase oxidation of SO2 in chamber process.
alkylation of hydrocarbons.
none of these.

Answer 44

alkylation of hydrocarbons.

Question 45

Fractional conversion __________ with increase in pressure for ammonia synthesis reaction i.e., N2 + 3H2 2NH3.
increases
decreases
remains unchanged
unpredictable from the data

Answer 45

increases

Question 46

Pick out the wrong statement.
The vessel dispersion number (D/UL) for plug flow and mixed flow approaches zero and infinity respectively.
Space time in a flow reactor is a measure of its capacity and is equal to the residence time when the density of reaction mixture is constant.
Mixed reactor is always smaller than the plug flow reactor for all positive reaction orders for a particular duty.
In an ideal tubular flow reactor, mixing takes place in radial direction and there is no mixing in logitudinal direction.

Answer 46

Mixed reactor is always smaller than the plug flow reactor for all positive reaction orders for a particular duty.

It should be “MR is always larger the PFR”

Question 47

The reason why a catalyst increases the rate of reaction is that, it
decreases the energy barrier for reaction.
increases the activation energy.
decreases the molecular collision diameter.
none of these.

Answer 47

decreases the energy barrier for reaction.

Question 48

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 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
none of these.

Answer 48

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

Question 49

When the density of the reaction mixture is constant in a chemical reaction, the ratio of the mean residence time to space time is
> 1
< 1
1
0

Answer 49

1

Question 50

In an ideal tubular-flow reactor
there is no mixing in longitudinal direction.
mixing takes place in radial direction.
there is a uniform velocity across the radius.
all (a), (b) and (c).

Answer 50

all (a), (b) and (c).

Question 51

At a given value of E/R (ratio of activation energy and gas constant), the ratio of the rate constants at 500°K and 400°K is 2, if Arrhenious law is used. What will be this ratio, if transition state theory is used with the same value of E/R?
1.6
2
2.24
2.5

Answer 51

2.5

Question 52

_________ is the controlling step in a highly temperature sensitive fluid-solid non-catalytic reaction.
Gas film diffusion
Ash diffusion
Chemical reaction
none of these

Answer 52

Chemical reaction

Question 53

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.
isothermal in nature.

Answer 53

completely self-supporting in its thermal energy requirements.

Question 54

The rate constant of a first order reaction depends on the _____.
concentration of the reactant.
temperature.
concentration of the product.
time.

Answer 54

temperature.

Question 55

A reaction in which one of the products of reaction acts as a catalyst is called a/an __________ reaction.
catalytic
autocatalytic
photochemical
none of these

Answer 55

autocatalytic

Question 56

The ratio of volume of mixed reactor to the volume of P.F.R. (for identical flow rate, feed composition and conversion) for zero order reaction is
∞
0
1
> 1

Answer 56

1

Question 57

Which of the following will favour the reverse reaction in a chemical equilibrium reaction ?
Increasing the concentration of one of the reactants.
Increasing the concentration of one or more of the products.
Removal of at least one of the products at regular interval.
None of these.

Answer 57

Increasing the concentration of one or more of the products.

Question 58

Conversion increases with increase in temperature in case of a an __________ reaction.
autocatalytic
irreversible
reversible endothermic
reversible exothermic

Answer 58

reversible endothermic

Question 59

Effective diffusivity (DE) in a catalyst pellet is related to molecular diffusivity (DN) and Knudsen diffusivity (DK) as
DE = DM + DK
1/DE = 1/DN + 1/DK
DE = DM . DE
DE = DN/DE

Answer 59

1/DE = 1/DN + 1/DK

Question 60

A photochemical reaction is __________ light.
initiated by
accompanied with emission of
catalysed by
used to convert heat energy into

Answer 60

initiated by

Question 61

Pick out the wrong statement.

In a batch reactor, which is exclusively used for liquid phase reactions; temperature pressure and composition may vary with time.
In a semi-batch reactor, one reactant is charged batchwise, while the other reactant is fed continuously.
In a continuous flow reactor, uniform concentration can not be maintained throughout the vessel even in a well agitated system.
In a continuous flow reactor, both the reactants and the products flow out continuously.

Answer 61

In a continuous flow reactor, uniform concentration can not be maintained throughout the vessel even in a well agitated system.

Question 62

In a/an __________ reactor, there is exchange of heat with the surroundings with sizeable temperature variation.
adiabatic
isothermal
non-adiabatic
none of these.

Answer 62

non-adiabatic

Question 63

‘Unreacted core model’ represents the reaction involving _____.
combustion of coal particles.
roasting of sulphide ores.
manufacture of carbon disulphide from elements.
none of these.

Answer 63

roasting of sulphide ores.

Question 64

For a vapour phase catalytic reaction (A + B P) which follows the Ridel mechanism and the reaction step is rate controlling, the rate of reaction is given by (reaction rate is irreversible, product also absorbs).

-rA = kPaPb/1+KaPa+KpPp
-rA = kPa2-k1Pp/1+KaPa+KpPp
-rA = kPaPb/1+KaPb+KbPbKpPp
-rA = kPaPb/1+KaPa

Answer 64

-rA = kPaPb/1+KaPa+KpPp

Question 65

If a solid-gas non-catalytic reaction occurs at very high temperature, the rate controlling step is the __________ diffusion.
film
ash layer
pore
none of these

Answer 65

film

Question 66

The units of frequency factor in Arhenious equation
are the same as those of the rate constant.
depend on the order of the reaction.
depend on temperature, pressure etc. of the reaction.
are cycles per unit time.

Answer 66

are the same as those of the rate constant.

Question 67

Which of the following is not a chemical step in a fluid solid catalytic reaction ?
Surface chemical reaction
Adsorption
Desorption
None of these

Answer 67

None of these

Question 68

For a series of reactions A→(k1)B→(k2)C having k1 &laquo_space;k2, the reaction system can be approximated as
a. A→(k1)B
b. A→(k2)B
c. A→(k2)C
d. A→(k1)C

Answer 68

d. A→(k1)C

Question 69

At a given temperature, K1, K2 and K3 are equilibrium constants for the following reactions 1, 2, 3 respectively.
CH4(g) + H2O(g) CO(g) + 3H2(g),
CO(g) + H2O(g) CO2(g) + H2(g)
CH4(g) + 2H2O(g) CO2(g) + 4H2(g)
Then K1, K2 and K3 are related as:

K3 = K1.K2
K3 = (K1.K2)^0.5
K3(K1+K2)/2
K3 = (K1.K2)^2

Answer 69

K3 = K1.K2

Question 70

In case of __________ reactions, the reaction rate does not decrease appreciably as the reaction proceeds.
catalytic
parallel
series
auto catalytic

Answer 70

auto catalytic

Question 71

For nearly isothermal operation involving large reaction time in a liquid-phase reaction, the most suitable reactor is a __________ reactor.
stirred tank
tubular flow
batch
fixed bed

Answer 71

stirred tank

Question 72

What is the Thiele modulus of the solid catalysed first order reaction, , if the pore diffusion offers negligible resistance to reaction ?
< 5
< 0.5
> 1
5

Answer 72

< 0.5

Question 73

B.E.T. method can be used to determine the __________ of a porous catalyst.
solid density
pore volume
surface area
all (a), (b) and (c)

Answer 73

surface area

Question 74

Rate constant for a first order reaction does not depend upon reaction time, extent of reaction and the initial concentration of reactants ; but it is a function of reaction temperature. In a chemical reaction, the time required to reduce the concentration of reactant from 100 gm moles/litre to 50 gm moles/litre is same as that required to reduce it from 2 gm moles/litre to 1 gm mole/litre in the same volume. Then the order of this reaction is
0
1
2
3

Answer 74

1

Question 75

Which of the following is an independent variable for a batch tank reactor with uniform concentration and temperature ?
Time
Useful volume of the tank
Diameter of the reactor
None of these

Answer 75

Time

Question 76

For a gaseous phase reaction, rate of reaction is equal to K. CA . CB. 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.
8
16
1/8
1/16

Answer 76

16

Question 77

In a reversible chemical reaction having two reactants in equilibrium, if the concentration of the reactants are doubled, then the equilibrium constant will
remain the same
be halved
also be. doubled
become one fourth

Answer 77

remain the same

Question 78

The equilibrium constant of a catalytic chemical reaction __________ due to the presence of a catalyst.
increases
decreases
remains unaffected
unpredictable from the data

Answer 78

remains unaffected

Question 79

The rate constant of a chemical reaction increases by increasing the
temperature
pressure
reactant’s concentration
none of these

Answer 79

temperature

Question 80

The catalytic activity of enzymes is due to their capacity to lower the __________ energy.
activation
potential
kinetic
none of these

Answer 80

activation

Question 81

A first order reaction requires two unequal sized CSTR. Which of the following gives higher yield ?
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, can’t be predicted.

Answer 81

Either of the arrangement (a) or (b) will give the same yield.

Question 82

Pick out the correct statement.
A lower temperature favours the reaction of lower activation energy.
The dispersion number for a reactor/vessel is uL/D.
The rate controlling step in a reaction involving many steps is the fastetst step.
Pore volume and porosity of a catalyst is measured by Brunaver-Emmet-Teller (BET) technique.

Answer 82

A lower temperature favours the reaction of lower activation energy.

Question 83

The effect of increasing pressure on the gaseous equilibrium of the reaction 2X+3Y 3X+2Y indicates that ____.
pressure has no effect.
backward reaction is favoured.
forward reaction is favoured.
none of these.

Answer 83

pressure has no effect.

Question 84

If in the gaseous phase reaction, N2O4 2NO2, x is the part of N2O4 which dissociates, then the number of molecules at equilibrium will be
(1 + x)
(1 - x)
(1 + x)2
(1 - x)2

Answer 84

(1 + x)

Question 85

A batch reactor is characterised by ______.
constant residence time.
variation in extent of reaction and properties of the reaction mixture with time.
variation in reactor volume.
very low conversion.

Answer 85

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

Question 86

When a catalyst increases the rate of forward reaction, the value of rate constant_____.
increases
decreases
remain same
becomes infinite

Answer 86

increases

Question 87

Rate determining step in a reaction consisting of a number of steps in series is the __________ step.
fastest
slowest
intermediate
data insufficient; can’t be predicted

Answer 87

slowest

Question 88

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 form 10 to 100°C.
256
512
112
612

Answer 88

512

Question 89

A catalyst in a chemical reaction __________ free energy change in the reaction.
increases
decreases
either (a) or (b); depends on the type of catalyst
neither (a) nor (b).

Answer 89

either (a) or (b); depends on the type of catalyst

Question 90

Signal normally used to study non-ideal flow by stimulus response technique is __________ input.
pulse
step
both (a) & (b)
neither (a) nor (b).

Answer 90

both (a) & (b)

Question 91

When all the limiting reactant is consumed in the reaction, the operational yield __________ the relative yield.
is greater than
is smaller than
equals
can be either greater or smaller than (depends on the type of reaction)

Answer 91

equals

Question 92

The half life period of a first order reaction is
always the same irrespective of the reaction.
independent on initial concentration of the reactants.
proportional to the initial concentration of reactants.
half the specific rate constant.

Answer 92

independent on initial concentration of the reactants.

Question 93

The catalyst in a second order reversible reaction increases the rate of the forward reaction ______.

and decreases that of backward reaction.
and backward reaction equally.
only.
to a greater extent than that of the backward reaction.

Answer 93

and backward reaction equally.

Question 94

Catalyst carriers
have very high selectivity.
increase the activity of a catalyst.
provide large surface area with a small amount of active material.
inhibit catalyst poisoning.

Answer 94

provide large surface area with a small amount of active material.

Question 95

For the liquid phase zero order irreversible reaction A B, the conversion of A in a CSTR is found to be 0.3 at a space velocity of 0.1min-1 . What will be the conversion for a PFR with a space velocity of 0.2 min-1? Assume that all the other operating conditions are the same for CSTR and PFR.
0.15
0.30
0.60
0.90

Answer 95

0.60

Question 96

A high space velocity means that a given
reaction can be accomplished with small reactor.
conversion can be obtained with a high feed rate.
both (a) and (b).
none of these.

Answer 96

both (a) and (b).

Question 97

In flow reactors, the performance equations interrelate the rate of reaction to the
feed rate.
reactor volume,
extent of reaction.
all (a), (b) and (c).

Answer 97

all (a), (b) and (c).

Question 98

Space velocity
describes the extensive operating characteristics of a tubular flow reactor.
is the maximum feed rate pre unit volume of reactor for a given conversion.
is a measure of the ease of the reaction.
all (a), (b) and (c)

Answer 98

all (a), (b) and (c)

Question 99

The rate of the chemical reaction A B doubles as the concentration of A i.e.., CA is doubled. If rate of reaction is proportional to CA^n, then what is the value of n for this reaction ?
0.5
1
0
2

Answer 99

1

Question 100

A reaction which is catalysed by a base is catalysed by all substances which have a tendency to
lose a proton
gain a proton
gain an electron
none of these

Answer 100

gain a proton

Question 101

For a homogeneous reaction of nth order, the dimension of the rate constant is given by
l/(time)n
(concentration)^(1 - n)/(time)
(concentration)^(n - 1)/(time)
none of these

Answer 101

(concentration)1 - n/(time)

Question 102

The fractional volume change between no conversion and complete conversion, for the isothermal gas phase reaction, 2A R, is
0.5
-0.5
1
1.5

Answer 102

-0.5

Question 103

The reaction in which one of the products of reaction acts as a catalyst is called a/an __________ reaction.
biochemical
photochemical
catalytic
autocatalytic

Answer 103

autocatalytic

Question 104

A typical example of an exothermic reversible reaction conducted at high pressure in industry is
dehydration of ethanol.
methanol synthesis.
reformation of methane.
polymerisation of ethylene.

Answer 104

dehydration of ethanol.

Question 105

Study of chemical kinetics is the easiest in the case of __________ reactions.
irreversible
reversible
surface
side

Answer 105

irreversible

Question 106

In autocatalytic reactions,
one of the reactants acts as a catalyst.
one of the products acts as a catalyst.
catalysts have very high selectivity.
no catalyst is used.

Answer 106

one of the products acts as a catalyst.

Question 107

Semibatch reactor is preferred, when a/an
a highly exothermic reaction is to be controlled.
undersirable side reaction (at high concentration of one of the reactants) is to be avoided.
a gas is to be reacted with liquid (e.g. hydrogenation of fat).
all (a), (b), and (c).

Answer 107

all (a), (b), and (c).

Question 108

For identical flow rate, feed composition and for elementary first order reactions, ‘N’ equal sized mixed reactors in series with a total volume ‘V’ gives the same conversion as a single plug flow reactor of volume ‘V’ for constant density systems. This is true, when the value of ‘N’ is
1
>1
∞
≥1

Answer 108

∞

Question 109

What is the order of a chemical reaction whose rate is deter-mined by the variation of one concentration term only ?
zero
first
second
third

Answer 109

first

Question 110

Pick out the wrong statement.
Visible radiation provides the necessary activation energy in photochemical reactions.
The order and molecularity of a complex reaction may not be the same.
For a second order reaction, the slope of the graph/plot between rate and (concentration) is equal to the rate constant (k).
Molecularity of the reaction is always a whole number greater than zero.

Answer 110

The order and molecularity of a complex reaction may not be the same.

Question 111

The rate at which a chemical substance reacts is proportional to its
active mass
equivalent weight
molecular weight
none of these

Answer 111

active mass

Question 112

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 ∫Edt,0,∞ is
0
1
∞
√2π

Answer 112

1

Question 113

A plug-flow reactor is characterised by
high capacity.
presence of axial mixing.
presence of lateral mixing.
constant composition and temperature of reaction mixture.

Answer 113

presence of lateral mixing.

Question 114

Three plug flow reactors (PFR’s) of 4, 5 & 6 m3 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.
100
150
200
225

Answer 114

100

Question 115

For a tubular reactor with space time ‘τ’ and residence time ‘θ’, the following statement holds good.
τ and θ are always equal.
τ = θ , when the fluid density changes in the reactor.
τ = θ , for an isothermic tubular reactor in which the density of the process fluid is constant.
τ = θ , for a non-isothermal reactor.

Answer 115

τ = θ , for an isothermic tubular reactor in which the density of the process fluid is constant.

Question 116

Rate of an autocatalytic chemical reaction is a function of
temperature only.
pressure only.
composition only.
all (a), (b) and (c).

Answer 116

all (a), (b) and (c).

Question 117

Which of the following curves shows the effect of temperature on the extent of gas-solid adsorption at a given pressure ?
Langmuir adsorption isotherm
Adsorption isobar
Freundlich adsorption isotherm
None of these

Answer 117

Adsorption isobar

Question 118

For an ideal mixed flow reactor (CSTR), the exit age distribution E(t) is given by
a dirac delta function
a step function.
a ramp function.
none of the above

Answer 118

none of the above

It should be an exponential function.
E(t) = e^(-t/τ)

Question 119

Fluid flow in a real packed bed can be approximated as __________ model.
plug flow
dispersion
mixed flow
tank in series

Answer 119

dispersion

Question 120

The ‘E’ curve for a non-ideal reactor defines the fraction of fluid having age between t and t + dt
at the inlet
at the outlet
in the reactor
averaged over the inlet and outlet

Answer 120

at the outlet

Question 121

To maximise the formation of R in the simultaneous reaction
A + B R , rR = 2CA0.5.CB2
A + B S , rS = 1.5 CA . CB
We should have
low CA, low CB
low CA, high CB
high CA, low CB
high CA, high CB

Answer 121

low CA, high CB

Question 122

A reaction which is catalysed by an acid is also catalysed by any substance, which has a tendency to
lose a proton.
gain a proton.
lose an electron
none of these.

Answer 122

lose a proton.

Question 123

A stirred tank reactor compared to tubular-flow reactor provides
more uniform operating conditions.
permits operation at the optimum temperature for a long reaction time.
higher overall selectivity for a first order consecutive reaction.
all (a), (b) and (c)

Answer 123

all (a), (b) and (c)

Question 124

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

Answer 124

1

Question 125

A catalyst inhibitor
lessens its selectivity.
may be useful for suppressing undesirable side reactions.
is added in small quantity during the catalyst manufacture itself.
all(a), (b) and (c).

Answer 125

all(a), (b) and (c).

Question 126

In chamber process of sulphuric acid manufacture in industry, the gas phase oxidation of SO2 to SO3 is accomplished by a __________ reaction.
non-catalytic homogeneous
non-catalytic heterogeneous
catalytic homogenous
catalytic heterogeneous

Answer 126

catalytic homogenous

Question 127

If the rate of a chemical reaction becomes slower at a given temperature, then the
initial concentration of the reactants remains constant.
free energy of activation is lower.
entropy changes.
free energy of activation is higher.

Answer 127

free energy of activation is higher.

Question 128

The conversion XA and residence time data are collected for zero order liquid phase reaction in a stirred tank reactor. Which of the following will be a straight line ?
XA Vs . τ
XA Vs ln τ
XA/(1 - XA)Vs τ
XA(1 - XA)Vs τ

Answer 128

XA Vs . τ

Question 129

The rate of the reaction, X → Y, quadruples when the concentration of ‘X’ is doubled. The rate expression for the reaction is, r = K Cx^n, the value of ‘n’ in this case will be
0
1
2
3

Answer 129

2

Question 130

The value of steric factor ‘P’ in the equation k = PZeE/RT usually ranges from
l.0 to 10-8
l.l.to 102
0.1 to 0.9
none of these

Answer 130

l.0 to 10-8

Question 131

For a zero order reaction, the concentration of product increases with the
increase of reaction time.
increase in initial concentration.
total pressure.
decrease in total pressure.

Answer 131

increase of reaction time.

Question 132

Pick out the wrong statement.
‘Hold back’ is defined as the fraction of material that stays longer than the mean residence time.
Study of non-ideal flow reactor is done experimentally by stimulus-response technique.
For studying a chemical reaction, it is desirable to monitor the reactants during initial stages and the products during the final stages of reaction.
A batch reactor can not be used to study the kinetics of catalytic reaction.

Answer 132

A batch reactor can not be used to study the kinetics of catalytic reaction.

Question 133

Effectiveness factor of a catalyst pellet is a measure of the __________ resistance.
pore diffusion
gas film
chemical reaction
none of these

Answer 133

pore diffusion

Question 134

The rate expression for a heterogenous catalytic reaction is given by, - rA = K.KA PA(1 + KA.PA + KR.PR), where K is surface reaction rate constant and KA and KR are absorption equilibrium constants of A and R respectively. If KR PR&raquo_space; (1 + KA PA), the apparent activation energy EA is equal to (given E is the activation energy for the reaction and ΔHR and ΔHA are the activation energies of adsorption of R and A)
E
E + ΔHA
E + ΔHA - ΔHR)
ΔHA + ΔHR

Answer 134

E + ΔHA - ΔHR)

Question 135

Given,
3H2 + CO = CH4 + H2O, KP = 101.84 and,
4H2 + CO2 = CH4 + 2H2O, KP = 101.17
the KP for the reaction CO + H2O = CO2 + H2 is
10^3.01
10^-0.67
10^-3.01
10^0.67

Answer 135

10^0.67

Question 136

Differential method for analysing the kinetic data is used
for testing complicated mechanisms.
when the data are scattered.
when rate expressions are very simple.
none of these.

Answer 136

for testing complicated mechanisms.

Question 137

In case of the irreversible unimolecular type, first order reaction, the fractional conversion at any time for constant volume system as compared to variable volume system is
more
less
same
either (a) or (b), depends on other factors

Answer 137

same

Question 138

The reaction in which the rate equation corresponds to a stoichiometric equation, is called a/an __________ reaction.
elementary
non-elementary
parallel
autokinetic

Answer 138

elementary

Question 139

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

Answer 139

0

Question 140

A first order gaseous phase reaction is catalysed by a non-porous solid. The kinetic rate constant and the external mass transfer co-efficients are k and kg respectively. The effective rate constant (keff) is given by
keff = k + kg
keff = (k+ kg)/2
keff = (kkg)1/2
1/keff = 1/k + 1/kg

Answer 140

1/keff = 1/k + 1/kg

Question 141

Arrhenious equation represents graphically the variation between the __________ and temperature.
rate of reaction
frequency factor
rate constant
activation energy

Answer 141

rate constant

Question 142

__________ catalytic reaction is involved in the thermal cracking of gas oil.
Homogeneous
Homogeneous non
Heterogeneous
Heterogeneous non

Answer 142

Homogeneous

Question 143

Variables affecting the rate of homogeneous reactions are
pressure and temperature only.
temperature and composition only.
pressure and composition only.
pressure, temperature and composition.

Answer 143

pressure, temperature and composition.

Question 144

A chemical reaction occurs when the energy of the reacting molecules is __________ the activation energy of the reaction.
less than
equal to
more than
equal to or more than

Answer 144

equal to or more than