Chemical Reactions Engineering Part 1

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.

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

A3B = 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 –> C , 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

2.82 9 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

(70 - 30) /10 = 4
2^4
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.

wrong one third reactor volume

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.

hpbr autoclave

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 ?
1
0.95
0.75
0.2

Answer 15

0.95

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 = K . CR .CS^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 = K . p^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

temperature

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
remain 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

For a reaction of the type, V –K1–> X –K2–> Y –K3–> Z , the rate of reaction (- rx) is given by
(K1+K1)CX
(K1+K2+K3)CX
K1CV - K2CX
(K1-K2)CX

Answer 25

K1CV - K2CX

Question 26

In a consecutive reaction system A –E1–> B –E2–> 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 26

increase of temperature.

Question 27

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 27

is at the highest allowable temperature throughout.

Question 28

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 28

9210 K

indiabix typo: *arrhenius theory

ln(k2/k1) = (E/R)(1/T1 - 1/T2)
ln100 = (E/R)(1/400 - 1/500)
E/R = 9210

Question 29

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 29

liquid phase reactions.

Question 30

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 30

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

Question 31

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 31

decrease in activation energy.

Question 32

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 32

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

Question 33

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 33

any

Question 34

Specific rate constant for a second order reaction
is independent of temperature.
varies with temperature.
depends on the nature of the reactants.
both (b) and (c).

Answer 34

both (b) and (c).

Question 35

For the irreversible elementary reactions in parallel viz X –k2–> Y; X–k1–> Z , the rate of disappearance of ‘X’ is equal to
CA(K1+K2)
CA(K1 + K2)/2
CA . K1/2
CA . K2/2

Answer 35

CA(K1+K2)

Question 36

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

Answer 36

CAo/(1+EAXA)(dXA/dt) = k

Question 37

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 linerarly with time.
all (a), (b) and (c).

Answer 37

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

Question 38

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

Answer 38

none of these.

Question 39

Radioactive decay follows __________ order kinetics.
first
second
third
zero

Answer 39

first

Question 40

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

Answer 40

activation

Question 41

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 41

chemical

Question 42

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 42

A catalyst lowers the activation energy of the reacting molecules.

Question 43

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

Answer 43

2

Question 44

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 44

Reactions with high activation energies are very temperature sensitive.

Question 45

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 45

2

Question 46

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 46

alkylation of hydrocarbons.

sulpuric catalyst alkylation of hydrocarbons

Question 47

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

Answer 47

increases

Question 48

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 48

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

wrong mixed always smaller than plug

Question 49

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 49

decreases the energy barrier for reaction.

Question 50

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 50

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

Question 51

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 51

1

Question 52

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 52

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

Question 53

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 53

2.5

Question 54

__________ 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 54

Chemical reaction

Question 55

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 55

completely self-supporting in its thermal energy requirements.

Question 56

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

Answer 56

temperature.

Question 57

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 57

autocatalytic

Question 58

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
infinite
0
1
> 1

Answer 58

1

Question 59

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 59

Increasing the concentration of one or more of the products.

Question 60

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

Answer 60

reversible endothermic

Question 61

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 61

1/DE = 1/DN + 1/DK

Question 62

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

Answer 62

initiated by

Question 63

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 63

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

Question 64

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

Answer 64

non-adiabatic

Question 65

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 65

roasting of sulphide ores.

Question 66

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 66

film

solid-gas non-cata very high temp - film diffusion

Question 67

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 67

are the same as those of the rate constant.

Question 68

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

Answer 68

None of these

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, x –k–> y, 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

BET 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 reactions in parallel viz A –>P (desired product) and A–>Q (unwanted product), if the order of the desired reaction is higher than that of the undesired reaction, a
batch reactor is preferred over a single CSTR for high yield.
tubular reactor is preferred over a single CSTR for high yield.
both (a) and (b).
single CSTR is the most suitable.

Answer 76

both (a) and (b).

Question 77

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 77

16

kCACB 1/4th 16

Question 78

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 78

remain the same

Question 79

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

Answer 79

remains unaffected

Question 80

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

Answer 80

temperature

Question 81

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

Answer 81

activation

Question 82

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 82

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

Question 83

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 83

A lower temperature favours the reaction of lower activation energy.

correct lower temp lower activation

Question 84

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 84

pressure has no effect.

Question 85

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 85

(1 + x)

(1+x) N2O4 2NO2

Question 86

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 86

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

Question 87

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

Answer 87

increases

Question 88

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 88

slowest

Question 89

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 89

512

(100 - 10) / 10 = 9
2^9
512

Question 90

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 90

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

Question 91

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

Answer 91

both (a) & (b)

Question 92

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 92

equals

Question 93

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 93

independent on initial concentration of the reactants.

Question 94

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 94

and backward reaction equally.

Question 95

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 95

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

Question 96

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
0.3
0.6
0.9

Answer 96

0.6

Question 97

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 97

both (a) and (b).

Question 98

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 98

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

Question 99

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 99

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

Question 100

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 CAn, then what is the value of n for this reaction ?
0.5
1
0
2

Answer 100

1

Question 101

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 101

gain a proton

Acid - lose proton
Base - gain proton

Question 102

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 102

(concentration)^1 - n/(time)

Question 103

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 103

-0.5

Question 104

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

Answer 104

autocatalytic

Question 105

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 105

dehydration of ethanol.

Question 106

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

Answer 106

irreversible

Question 107

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 107

one of the products acts as a catalyst.

Question 108

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 108

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

Question 109

Exposure of a photographic plate to produce a latent image is an example of __________ reaction.
very slow
very fast
photochemical
both (b) and (c)

Answer 109

both (b) and (c)

Question 110

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
infinite
>=1

Answer 110

infinite

Question 111

Helium-mercury method is used for the measurement of the __________ of the catalyst.
surface area
porosity
pore volume
both (b) & (c).

Answer 111

both (b) & (c).

Question 112

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 112

first

Question 113

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 113

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

Question 114

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

Answer 114

active mass

Question 115

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 integral of E dt from 0 to infinity is
0
1
infinite
sqrt(2.pi)

Answer 115

1

Question 116

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 116

presence of lateral mixing.

Question 117

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 117

100

Question 118

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

Answer 118

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

Question 119

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

Answer 119

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

Question 120

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 120

Adsorption isobar

extent given pressure isoBAR

Question 121

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 121

none of the above

Question 122

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

Answer 122

dispersion

Question 123

For series reaction, the relative yield
is always greater for plug-flow reactor than for the single CSTR of the same volume.
statement in (a) is wrong.
decreases with increasing conversion.
both (a) and (c) hold good.

Answer 123

both (a) and (c) hold good.

Question 124

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 124

at the outlet

‘E’ t ~ t + dt outlet

Question 125

To maximise the formation of R in the simultaneous reaction
A + B –> R , rR = 2CA^0.5.CB^2
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 125

low CA, high CB

Question 126

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 126

lose a proton.

Acid - lose proton
Base - gain proton

AL-BG

Question 127

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 127

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

Question 128

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 128

1

Question 129

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 129

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

Question 130

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 130

catalytic homogenous

sulphuric acid cata-homo

Question 131

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 131

free energy of activation is higher.

rate slower EA higher

Question 132

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 . T
XA Vs ln T
XA/(1 - XA)Vs T
XA(1 - XA)Vs T

Answer 132

XA Vs . T

Question 133

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 133

2

Question 134

The value of steric factor ‘P’ in the equation k = PZe^E/RT usually ranges from
1.0 to 10^-8
1.1 to 10^2
0.1 to 0.9
none of these

Answer 134

1.0 to 10^-8

steric10108

steric 1.0 to 10^-8

Question 135

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 135

increase of reaction time.

Question 136

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 136

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

wrong batch cannot kinetics

Question 137

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

Answer 137

pore diffusion

Question 138

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 138

E + ΔHA - ΔHR)

EHAHR

Question 139

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 139

10^0.67

Question 140

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 140

for testing complicated mechanisms.

differential - complicated

Question 141

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 141

same

Question 142

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

Answer 142

elementary

Question 143

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 143

0

Question 144

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 144

1/keff = 1/k + 1/kg

Question 145

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

Answer 145

rate constant

Question 146

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

Answer 146

Homogeneous

Question 147

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 147

pressure, temperature and composition.

Question 148

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 148

equal to or more than

Question 149

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

Answer 149

Ash resistance.

Question 150

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
zero
one
two
three

Answer 150

one

Question 151

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

Answer 151

10 C

Question 152

If CA is the quantity of reactants initially present, the quantity left after ‘n’ half periods will be equal to
(CA/2)^n
(1/2)^n.CA
(CA/2)^1/n
(CA)^1/2n

Answer 152

(1/2)^n.CA

Question 153

A photochemical reaction is
accompanied with emission of light.
catalysed by light.
initiated by light.
all (a), (b) & (c).

Answer 153

initiated by light.

Question 154

The optimum performance for reactors operating in parallel is obtained when the feed stream is distributed in such a way, that the
space time for each parallel line is same.
space time for parallel lines is different.
larger reactors have more space time compared to smaller ones.
none of these.

Answer 154

space time for each parallel line is same.

Question 155

A catalyst is said to be a negative catalyst, ifit
retards the rate of reaction.
reduces the value of equilibrium constant.
does not initiate the reaction.
all (a), (b) and (c).

Answer 155

retards the rate of reaction.

Question 156

For the non catalytic reaction of particles with surrounding fluid, the same needed to achive the same fractional conversion for particles of different unchanging sizes is proportional to the particle diameter, when the __________ is the controlling resistance.
film diffusion
diffusion through ash layer
chemical reaction
either (a), (b) or (c)

Answer 156

chemical reaction

Question 157

Pure ethanol vapor is fed to a reactor packed with alumina catalyst, at the rate of 100 kmole / hr. The reactor products comprise: ethylene :95 kmole / hr, water vapour: 97.5 k mole / hr and diethyl ether :2.5 kmole/hr. The reactions occuring can be represented by:
C2H5OH C2H4 + H2O
2C2H5OH C2H5 - O - C2H5 + H2O
The percent conversion of ethanol in the reactor is
100
97.5
95
2.5

Answer 157

100

Pure ethanol vapor 100 kmole/hr 100 percent conversion

Question 158

Pick out the wrong statement.
The integral method of analysing kinetic data is used when the data is scattered.
The differential method of analysing kinetic data requires more accurate or larger amounts of data.
When the reaction rate is independent of temperature, the reaction is said to be of zero order.
The ratio of volumes of plug flow reactor to that of mixed reactor is always less than one for identical feed composition, flow rate, conversion and for all positive reaction orders.

Answer 158

When the reaction rate is independent of temperature, the reaction is said to be of zero order.

Question 159

A backmix reactor
is same as plug-flow reactor.
is same as ideal stirred tank reactor.
employs mixing in axial direction only.
is most suitable for gas phase reaction.

Answer 159

is same as ideal stirred tank reactor.

Question 160

Rate of a chemical reaction is not influenced by the
catalyst
temperature
reactants concentration
number of molecules of reactants taking part in a reaction

Answer 160

number of molecules of reactants taking part in a reaction

Question 161

Pick out the wrong statement:
Chemical reactions with high activation energy are very temperature sensitive.
A flat velocity profile exists in a plug flow reactor.
The residence time for all the elements of fluid in case of a P.F.R. need not be same.
Half life of a reaction increases with increased initial concentration for reaction orders more than one.

Answer 161

The residence time for all the elements of fluid in case of a P.F.R. need not be same.

wrong residence need not be same

Question 162

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))
400
500
600
1000

Answer 162

600

Question 163

Which of the following is not a theory of homogeneous reaction?
Collision theory and activated complex theory
Chain reaction theory
Radiation hypothesis
None of these

Answer 163

None of these

Question 164

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

Answer 164

III, II, I

Question 165

In a semi-batch reactor,
mixing takes place in axial direction only.
velocity of reaction can be controlled.
condition similar to plug flow reactor exists.
residence time is constant.

Answer 165

velocity of reaction can be controlled.

Question 166

Most important characteristics of gas-liquid reactors are the
specific inter-facial area
liquid hold-up
both (a) and (b)
none of these

Answer 166

both (a) and (b)

Question 167

Which of the following is a controlling factor in very fast heterogeneous reaction?
Heat and mass transfer effects
Pressure
Temperature
Composition of reactant

Answer 167

Heat and mass transfer effects

Question 168

Enzymes are destroyed, when the
temperature is very high,
reactant’s concentration is very high.
reactant’s concentration is very low.
reaction rate is independent of the reactant’s concentration.

Answer 168

temperature is very high,

Question 169

For an autocatalytic reactor, the suitable reactor set up is
P.F. reactors in series.
CSTR in series.
CSTR followed by P.F. reactor.
P.F. reactor followed by CSTR.

Answer 169

CSTR followed by P.F. reactor.

Question 170

Ionic reactions occur in
solid state only
liquid state only
solutions
any state

Answer 170

solutions

Question 171

Sometimes, batch process is preferred over continuous process, when the product
quality & yield can not be achieved in continuous processes, because of long residence time.
sales demand is fluctuating.
both (a) & (b).
neither (a) nor (b).

Answer 171

both (a) & (b).

Question 172

In a chemical reaction X + Y + Z –k–> P , it is observed that the
(i) rate of formation of ‘P’ is doubled on doubling the concentration of ‘X’.
(ii) rate of formation of ‘P’ is quadrupled on doubling the concentration of ‘Y’.
(iii) doubling the concentration of ‘Z’ does not affect the rate of formation of ‘P’.
What is the order of the above chemical reaction?
Zeroth order
First order
Second order
Third order

Answer 172

Third order

Question 173

The half life period of a first order reaction is given by (where, K = rate constant. )
1.5K
2.5 K
0.693/K
6.93 K

Answer 173

0.693/K

first order - ln2/K = 0.693/K

Question 174

Half life period of a chemical reaction is
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.
none of these

Answer 174

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

Question 175

In the gaseous phase ammonia formation reaction (N2 + 3H2<–>2NH3), the value of the equilibrium constant depends on the
total pressure of the system.
volume of the reactor.
temperature.
initial concentration of N2 and H2.

Answer 175

temperature.

Question 176

Transition state theory relates the above quantities as
k is proportional to e^-E/RT
k is proportional to T.e^E/RT
k is proportional to sqrt(T)
k is proportional to T1.5

Answer 176

k is proportional to T.e^E/RT

Question 177

Photochemical reaction rate does not depend significantly on temperature, because
it is a reversible reaction.
it is an exothermic reaction.
the energy of reacting molecules exceeds the activation energy by absorption of light.
none of these.

Answer 177

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

Question 178

A CSTR is to be designed in which an exothermic liquid phase first order reaction of the type, A–>R, is taking place. The reactor is to be provided with a jacket in which coolant is flowing. Following data is given: CA0= 5 kmole/m3 ; XA = 0.5; Feed temperature = reactor temperature = 40 C. Rate constant at 40 C = 1 min-1 ; (delta-H) = - 40kJ/mole; ? = 1000kg/m3 CP = 4 J/gm. C ; q = 10-3 m3/min (? and CP are same for the reactant and product streams). The amount of heat to be removed is
2/3 kW
1kW
5/3 kW
4kW

Answer 178

5/3 kW

Question 179

According to the ‘law of mass action’, the rate of reaction is directly proportional to the
equilibrium constant.
volume of the reaction vessel.
nature of the reactants.
molar concentration of the reactants.

Answer 179

molar concentration of the reactants.

Question 180

In a chemical reaction, __________ are conserved.
ions
masses
atoms
both(b) & (c)

Answer 180

both(b) & (c)

Question 181

For an ideal gas mixture undergoing a reversible gaseous phase chemical reaction, the equilibrium constant
is independent of pressure.
increases with pressure.
decreases with pressure.
increases /decreases with pressure depending on the stoichiometric co-efficients of the reaction.

Answer 181

increases with pressure.

Question 182

In the reversible reaction of the type, A + B <–> AB, in general
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.

Answer 182

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

Question 183

A batch reactor is
suitable for gas-phase reactions on commercial scale.
suitable for liquid phase reactions involving small production rate.
least expensive to operate for a given rate.
most suitable for very large production rate.

Answer 183

suitable for liquid phase reactions involving small production rate.

batch liquid small production

Question 184

For a first order reaction carried out in a plug flow reactor, the space time is
1/K ln Co/C
1/K ln C/Co
K ln Co/C
K ln C/Co

Answer 184

1/K ln Co/C

Question 185

For an isothermal second order aqueous phase reaction, A –> B, the ratio of the time required for 90% conversion to the time required for 45% conversion is
2
4
11
22

Answer 185

11

904511 90% 45% 11

Question 186

A chemical reaction is of zero order, when the reaction rate is (where, CA = concentration of reactant)
is proportional to CA.
is proportional to 1/CA.
independent of temperature.
none of these.

Answer 186

none of these.

Question 187

Second order consecutive irreversible reactions A –k1–> B –k2–> C 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 B to that of A in the initial feed was less than 0.5, the concentration of B 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 (k1/k2)?
14
12
2
4

Answer 187

14

Question 188

Pick out the wrong statement.
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.

Answer 188

Enzymes help in increasing the activation energy of the reaction.

wrong - Enzymes help…

Question 189

There is no correspondence between stoichiometry and the rate equation in case of a/an __________ reaction.
elementary
multiple
autocatalytic
non-elementary

Answer 189

non-elementary

Question 190

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/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.

Answer 190

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

spherical porous - R/8 does not

Question 191

Which of the following is used for calcination of limestone and dolomite in industrial practice ?
Fluidised bed reactor
Moving bed reactor
Fixed bed reactor
None of these

Answer 191

Moving bed reactor

DLMB dolomite limestone moving bed

Question 192

An imbalanced chemical reaction equation is against the law of
multiple proportion
conservation of mass
constant proportion
none of these

Answer 192

conservation of mass

Question 193

For the chemical reaction P Q, it is found that the rate of reaction doubles as the concentration of ‘P’ is doubled. If the reaction rate is proportional to Cpn, then what is the value of ‘n’ for this chemical reaction ?
1
2
3
0

Answer 193

1

Question 194

Which of the following is a characteristic of an ideal plug flow reactor ?
Axial dispersion
Flat velocity profile
Uniform mixing
None of these

Answer 194

Flat velocity profile

Question 195

Velocity of a reaction depends upon the
nature of the reactants.
concentration of the reactants.
temperature at which the reaction is carried.
all (a), (b) and (c).

Answer 195

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

Question 196

Threshold energy in a reaction is equal to the
activation energy
normal energy of reactants
sum of (a) & (b)
neither (a) nor (b)

Answer 196

sum of (a) & (b)