Chemical Reactions Engineering Part 3

Question 1

For the same residence time, which one will give the maximum conversion ?
Single stirred tank (v = 5 litres).
Two stirred tank (each of 2.5 litres) in series.
Stirred tank followed by tubular flow reactor (each of 2.5 litres).
Single tubular flow reactor (v = 5 litres).

Answer 1

Single tubular flow reactor (v = 5 litres).

Question 2

__________ gas is normally employed in B.E.T.method of finding out the surface area of catalyst.
N2
H2
CO2
He

Answer 2

N2

Question 3

The exit age distribution curve E(t) for an ideal CSTR with the average residence time, T, is given by
e^-t/T
[(e^-t/T)/T]
1 - e^-t/T
1-[(e^-t/T)/T]

Answer 3

[(e^-t/T)/T]

etTT

Question 4

The rate constant of a reaction depends on the
initial concentration of reactants.
time of reaction.
temperature of the system.
extent of reaction.

Answer 4

temperature of the system.

Question 5

For the reversible reaction A <–>2B, if the equilibrium constant K is 0.05 mole/litre; starting from initially 2 moles of A and zero moles of B, how many moles will be formed at equilibrium ?
0.253
0.338
0.152
0.637

Answer 5

0.338

Question 6

For identical flow rate and feed composition, X plug flow reactors (PER) in series with a total volume V gives the same conversion as single
CSTR of volume V
PFR of volume V
CSTR of volume V/X
PFR of volume V/X

Answer 6

PFR of volume V

Question 7

Time required for 50% decomposition of a liquid in an isothermal batch reactor following first order kinetics is 2 minutes. The time required for 75% decomposition will be about __________ minutes.
3
4
6
8

Answer 7

4

Question 8

For a __________ order reaction, the units of rate constant and rate of reaction are the same.
zero
first
second
fractional

Answer 8

zero

Question 9

In case of staged packed bed reactors carrying out exothermic reaction, use
high recycle for pure gas.
plug flow for dilute liquid requiring no large preheating of feed.
cold shot operations for a dilute solution requiring large preheating to bring the stream upto the reaction temperature.
all (a), (b) and (c).

Answer 9

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

Question 10

Vegetable oils are hydrogenated in a __________ reactor.
slurry
plug flow
homogeneous catalytic
none of these

Answer 10

slurry

veg oil slurry

Question 11

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

Answer 11

1/3

gas 50% A3B 1/3 mole fraction

Question 12

The rate of reaction does not decrease appreciably as the reaction proceeds in case of __________ reactions.
autocatalytic
exothermic
endothermic
autothermal

Answer 12

autocatalytic

Question 13

For all positive reaction orders for a particular duty,
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.

Answer 13

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

Question 14

The heat of reaction
depends on the pressure only.
depends on the mechanism of reaction only.
depends on both pressure and mechanism of reaction.
is independent of the mechanism of reaction.

Answer 14

is independent of the mechanism of reaction.

Question 15

Which of the following does not produce a change in the value of rate constant of a reaction ?
Pressure
Temperature
Concentration and catalyst
None of these.

Answer 15

Concentration and catalyst

Question 16

With increase in temperature, the equilibrium conversion of a reversible exothermic reaction
decreases
increases
remains unaffected
decreases linearily with temperature

Answer 16

decreases

Question 17

In a CSTR __________ varies with time.
reaction rate
concentration
both (a) & (b)
neither (a) nor (b)

Answer 17

neither (a) nor (b)

Question 18

The following gas phase reactions are carried out isothermally in a CSTR.
A –> 2R ; r1 = k1pA ;
k1 = 20mole/(sec.m3 bar)
A –> 3S ; r2 = k2 pA ;
k2 = 40mole/(sec.m3 .bar)
What is the maximum possible value of FR(mole/sec.) ?
1/3
1/2
2/3
2

Answer 18

2/3

Question 19

As the chemical reaction proceeds, the rate of reaction
increases.
decreases.
remains same.
may increase or decrease depending on the type of reaction.

Answer 19

decreases.

Question 20

Pick out the wrong statement.
A catalyst does not alter the final position of equilibrium in a reversible reaction.
A catalyst initiates a reaction.
A catalyst is specific in reaction.
A catalyst remains unchanged in chemical composition at the end the reaction.

Answer 20

A catalyst initiates a reaction.

Question 21

In a first order reaction, the time required to reduce the concentration of reactant from 1 mole/litre to 0.5 mole/litre will be __________ that required to reduce it from 10 moles/litre to 5 moles/litre in the same volume.
more than
less than
same as
data insufficient; can’t be predicted.

Answer 21

same as

1 0.5 10 5 same as

Question 22

Photo-chemical reactions occur in presence of
sunlight.
darkness.
solid catalysts.
monochromatic radiation only.

Answer 22

sunlight.

Question 23

n’ number of plug flow reactors (P.F.R) in series with a total volume ‘V’ gives the same conversion as one P.F.R. of volume
V/n
V
V.n
1/V

Answer 23

V

Question 24

Knudsen diffusion is directly proportional to
T
sqrt(T)
1/sqrt(T)
T^2

Answer 24

sqrt(T)

Question 25

Fractional conversion __________ for an exothermic reversible chemical reaction, when the temperature is maximum.
increases
remains unchanged
decreases
unpredictable from the data

Answer 25

decreases

Question 26

Non-catalytic fluid-solid reactions are represented by __________ model.
continuous reaction
unreacted core
both (a) and (b)
neither (a) and (b)

Answer 26

both (a) and (b)

Question 27

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

Answer 27

2T

pulse tracer 2T

Question 28

On application of pressure to the equilibrium system, ice <–> water ; which of the following phenomenon will occur ?
Water will evaporate
Equilibrium will not be attained
More ice will be formed
More water will be formed.

Answer 28

More water will be formed.

pressure ice water more water

Question 29

Participation of __________ is involved in the occurrence of a chemical reaction.
protons
neutrons
electrons
none of these

Answer 29

electrons

Question 30

Promoter.
initiates a chemical reaction and is a catalyst by itself.
atlers the position of equilibrium in a reversible reaction.
increases the number of active centres by increasing the unevenness of catalyst surface and by creating discontinuities in the crystals.
all (a), (b) and (c).

Answer 30

increases the number of active centres by increasing the unevenness of catalyst surface and by creating discontinuities in the crystals.

Question 31

The rate constant of a reaction is a function of the
time of reaction.
temperature of the system.
extent of reaction.
initial concentration of the reactants.

Answer 31

temperature of the system.

Question 32

Mean residence time is equal to the space time, when
the feed rate is measured at temperature and pressure in the reactor.
the temperature, pressure and the density of reaction mixture remains constant throughout the reactor.
there is no change in number of moles in gaseous reaction.
all (a), (b) and (c).

Answer 32

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

Question 33

If ‘n’ is the order of reaction, then unit of rate constant is
1/(time)(concentration)^n - 1
(time)^-1 (concentration)^n - 1
(time)^n - 1 (concentration)
none of these

Answer 33

1/(time)(concentration)^n - 1

Question 34

Batch process is preferred over continuous process, when the
product yields and quality can not be achieved in continuous process, because of long residence time.
sales demand of product is not steady.
same equipment can not be used for several processes of the same nature.
all (a), (b) & (c)

Answer 34

all (a), (b) & (c)

Question 35

The value of ‘n’ for a chemical reaction A –> B, whose reaction rate is –>CAn, will be __________ if the rate of the reaction increases by a factor of 8, when the concentration of is doubled.
0
1
2
3

Answer 35

3

Question 36

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

Answer 36

higher in P.F. reactor

Question 37

For any reaction, we may write conversion as a function of
time
temperature
concentration
all (a), (b) & (c)

Answer 37

all (a), (b) & (c)

Question 38

The use of space time is preferred over the mean residence time in the design of a/an
batch reactor
ideal tubular-flow reactor
slurry reactor
CSTR

Answer 38

ideal tubular-flow reactor

space time preferred - ideal tubular-flow

Question 39

Autocatalytic reactions are best carried out in a
CSTR
CSTR in series
plug flow reactor
recycle reactor

Answer 39

recycle reactor

Question 40

The gas phase reaction 2A <–> B is carried out in an isothermal plug flow reactor. The feed consists of 80 mole % A and 20 mole % inerts. If the conversion of A at the reactor exit is 50%, then CA/CA0 at the outlet of the reactor is
2/3
5/8
1/3
3/8

Answer 40

5/8

2AB 80% 20% 50% 5/8

Question 41

A batch reactor suffers from following disadvantage.
Poor product quality control.
High labour and handling cost.
High shutdown time requirement for emptying, cleaning and refilling.
All (a), (b)and(c).

Answer 41

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

Question 42

A first order reaction is to be treated in a series of two mixed reactors. The total volume of the two reactors is minimum, when the reactors are
equal in size.
of different sizes.
of such size that the ratio of their volumes is < 5.
none of these.

Answer 42

equal in size.

Question 43

Half life period of a chemical reaction is proportional to CA0-1 , if the reaction is of __________ order.
first
zero
second
third

Answer 43

second

Question 44

The irreversible reaction, X –> Y, is the special case of the reversible reaction, X <–>Y, in which the
equilibrium constant is infinite.
fractional conversion of ‘A’ at equilibrium is unity.
concentration of ‘A’ at equilibrium is zero.
all (a), (b) and (c).

Answer 44

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

Question 45

The equilibrium constant K of a chemical reaction depends on
temperature only.
pressure only.
temperature and pressure.
ratio of reactants.

Answer 45

temperature only.

Question 46

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.
collision frequency increases.
value of threshold energy decreases.

Answer 46

fraction of molecules having threshold energy increases.

Question 47

Which of the following is not a unit of reaction rate ?
Moles for med/(surface of catalyst) (time)
Moles formed/volume of reactor) (time)
Mole formed/volume of catalyst) (time)
None of these

Answer 47

None of these

Question 48

Brunaur, Emmet and Teller (BET) equation is used to determine the specific surface area of a porous particle but not the pore volume & the porosity of the catalyst bed. Which of the following postulates is not used to derive BET equation ?
Langmuir’s assumption applies to every adsorbed layer.
There is no dynamic equilibrium between successive layer.
The adsorbed layer may be polymolecular in thickness and the heat of adsorption in each layer (except the first one) is involved in each of the evaporation process.
none of these.

Answer 48

There is no dynamic equilibrium between successive layer.

not BET no dynamic

Question 49

The sequence in which three CSTR’s of volumes 5, 10 and 15 m3 will be connected in series to obtain the maximum production in a second order irreversible reaction is
15, 10, 5
5, 10, 15
10, 5, 15
10, 15, 5.

Answer 49

15, 10, 5

5, 10 and 15 = 15, 10, 5

Question 50

The following half life data are available for the irreversible liquid phase reaction A products.
Initial Concentrations (K.mol/m^3): 2 and 8 and Half-lifes: 2 and 1, respectively. The overall order of reaction is
0.5
1
1.5
2

Answer 50

1.5

Question 51

A non-catalytic chemical reaction of the type A –+Z,K1–> B –+Z,K2–> C –+Z,K–> D is called a __________ reaction.
parallel
series
series-parallel
none of these

Answer 51

series-parallel

Question 52

The unit of frequency factor in Arhenious equation is
same as that of rate constant.
same as that of activation energy.
dimensionless.
none of these.

Answer 52

same as that of rate constant.

Question 53

With increase in the order of reaction (for all positive reaction orders), the ratio of the volume of mixed reactor to the volume of plug flow reactor (for identical feed composition, flow rate and conversion)
increases
decreases
remains same
increases linearly

Answer 53

increases

Question 54

Reaction of benzene with chlorine gas to produce tri-chlorobenzene exemplifies a/an __________ reaction.
elementary
parallel
consecutive
none of these

Answer 54

consecutive

Question 55

For the gaseous reaction 2A –> B, where the feed consists of 50 mole % A and 50 mole % inerts, the expansion factor is
1
-0.5
-0.25
0

Answer 55

-0.25

Question 56

The molecularity and the order of reaction respectively, for the hydrolysis of methyl acetate in presence of acids are
2 & 1
11 & 2
2 && 2
1 & 1

Answer 56

2 & 1

Question 57

The irreversible reaction is a special case of reversible reaction, if the
equilibrium constant is 1.
conversion of the reactant at equilibrium condition is zero.
reactant concentration at equilibrium condition is zero.
all (a), (b) and (c).

Answer 57

reactant concentration at equilibrium condition is zero.

Question 58

A pollutant P degrades according to first order kinetics. An aqueous stream containing P at 2 kmole/m3 and volumetric flow rate 1m3 /h requires a mixed flow reactor of volume V to bring down the pollutant level to 0.5 kmole/m3 . The inlet concentration of the pollutant is now doubled and the volumetric flow rate is tripled. If the pollutant level is to be brought down to the same level of 0.5 kmole/m3 , the volume of the mixed flow reactor should be increased by a factor of
7
6
3
7/3

Answer 58

7

V/1 = Cao Xa/kCao(1-Xa) = Xa/k(1-Xa)
Xa = 1-Ca/Cao = 1-0.5/2 = 0.75.
V = 0.75/kx0.25 = 3/k —— (1).
V2/3 = Xa/k(1-Xa).
Xa = 1-Ca/Cao = 1-0.5/4 = 0.875.
V2/3 = 0.875/k(0.125) = 7/k ——(2).

Dividing (2) by (1),
(V2/3)/V = (7/k)/(3/k).
V2/3V = 7/3.
V2 = 7V.

Question 59

For the liquid phase parallel reactions:
R, rR = K1.CA2; E1 = 80 KJ/mole
S, rs= K1.CA ; E2 = 120 KJ/mole
The desired product is R. A higher selectivity of R will be achieved, if the reaction is conducted at
low temperature in a CSTR.
high temperature in a CSTR.
low temperature in a PFR.
high temperature in a PFR.

Answer 59

high temperature in a PFR.

Question 60

In an ideal mixed reactor (at steady state), the
space time is equivalent to holding time for constant density systems.
composition throughout the reactor remains same.
exit stream has the same composition as the fluid within the reactor.
all (a), (b) and (c).

Answer 60

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

Question 61

The knowledge of initial concentration and rate constant is necessary to determine the half life time of a reaction of __________ order.
zero
first
second
none of these

Answer 61

second

Question 62

Which of the following factors control the design of a fluid-solid reactor ?
Reaction kinetics for single particle,
Size distribution of solids beingtreated.
Flow patterns of solids and fluid in the reactor.
All (a), (b) and (c).

Answer 62

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

Question 63

A Catalyst
increases the equilibrium concentration of the product.
changes the equilibrium constant of the reaction.
shortens the time to reach the equilibrium.
none of these.

Answer 63

shortens the time to reach the equilibrium.

Question 64

The synthesis of proteins and metabolism in biological objects occur in the presence of biocatalyst called
a ferment or an enzyme
haemoglobin
fungi
none of these

Answer 64

fungi

synthesis of proteins biocatalyst fungi

Question 65

Pick out the wrong statement.
A particular chemical reaction is more temperature sensitive at low temperatures.
A very high value of equilibrium constant, K (K&raquo_space; 1) indicates that the reaction is practically irreversible in nature.
The intercept of the Arrhenious plot is called the ‘activation energy’.
Non-ideal flow takes place in reactors due to recycling, channeling or by creation of stagnant regions.

Answer 65

The intercept of the Arrhenious plot is called the ‘activation energy’.

Question 66

Kinetics of a catalytic reaction can be best studied on a/an __________ reactor.
mixed
integral (plug flow)
differential (flow)
either (a), (b) and (c).

Answer 66

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

Question 67

In case of a __________ reactor, the composition in the reactor and at the exit of the reactor is the same.
semi-batch
tubular
batch
back-mix

Answer 67

back-mix

Question 68

Exothermic reactions are best carried out in
a CSTR.
CSTR in series.
a plug flow reactor followed by CSTR.
CSTR followed by a plug flow reactor.

Answer 68

CSTR followed by a plug flow reactor.

Question 69

What is the order of chemical reaction A + B + C –K–> D , if itis found that the reaction rate doubles on doubling the concentration of B and also the reaction rate doubles when the concentrations of both A & B were doubled and quandrupled when the concentrations of both B & C were doubled ?
1
2
3
4

Answer 69

2

Question 70

Reactions with high activation energy are
very temperature sensitive
temperature insensitive
always irreversible
always reversible

Answer 70

very temperature sensitive

Question 71

If n = overall order of a chemical reaction. a = initial concentration of reactant. t = time required to complete a definite fraction of the reaction. Then pick out the correct relationship.
t is proportional to 1/a^n
t is proportional to 1/a^n-1
t is proportional to 1/a^n+1
t is proportional to a^n

Answer 71

t is proportional to 1/a^n-1

Question 72

In case of a/an __________ chemical reaction, conversion increases with the rise in temperature.
reversible exothermic
irreversible exothermic
irreversible endothermic
reversible endothermic

Answer 72

reversible endothermic

Question 73

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

Answer 73

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

Question 74

With increase in initial concentration, the fractional conversion of a first order reaction in a given time
increases
decreases
remains constant
unpredictable

Answer 74

remains constant

Question 75

The rate of reaction of a/an __________ reaction is not affected by temperature rise.
autocatalytic
photochemical
consecutive
zero order.

Answer 75

photochemical

Question 76

With an increase in pressure in gaseous phase chemical reactions, the fractional conversion __________ when the number of moles decreases.
increases
decreases
remains unaffected
unpredictable from the data

Answer 76

increases

Question 77

Half-life period for a first order reaction is __________ the initial concentration of the reactant.
directly proportional to
inversely proportional to
independent of
none of these

Answer 77

independent of

Question 78

Carbon particles accummulated on the catalyst used in the gas oil cracking lies in the category of __________ poison.
deposited
chemisorbed
selectivity
stability

Answer 78

deposited

carbon on catalyst deposited poison

Question 79

The order of the chemical reaction, 2A + B –K–> C, whose rate equation is given as -rA= KCA2. CB is
0
1
2
3

Answer 79

3

Question 80

What is the dispersion number for a plug flow reactor ?
0
infinite
1
-1

Answer 80

0

Question 81

The decomposition of A into B is represented by the exothermic reaction, A <–> 2B. To achieve maximum decomposition, it is desirable to carry out the reaction.
at high P and high T.
at low P and high T.
at low P and low T.
at high P and low T.

Answer 81

at low P and low T.

Question 82

The catalytic converter for conversion of SO2 to SO3 by contact process should have a feed with SO2 content between
2-5%
7-10%
12-15%
20-25%

Answer 82

7-10%

Question 83

If the pore diffusion controls in a catalytic reaction, the apparent activation energy Ea is equal to
the intrinsic activation energy E.
(E + ED) where ED is activation due to diffusion.
(E + ED)/2
ED/2

Answer 83

ED/2

Question 84

With increase in K2/K1 in case of a unimolecular type elementary reactions A –K1–> R –K2–> S , the fractional yield of ‘R’ in mixed reactor (for a given conversion of ‘A’)
decreases
increases
increases linearly
remains same

Answer 84

decreases

Question 85

Collision theory gives the rate constant for bimolecular reaction as
K α √T.e^-E/RT
K α e^E/RT
K α e^-E/RT
none of these

Answer 85

K α e^-E/RT

typo error
arrhenius → K α e^-E/RT
transition state → K α T . e^-E/RT
collision → K α √T. e^-E/RT

just memorize the typo answer

collision - bimolecular - e^-E/RT

Question 86

Find a mechanism that is consistent with the rate equation and reaction given below:
2A + B –> A2B, ( - rA) = k.CA.CB
A + B <–> AB ; AB + A –>A2B
A + B –> AB;AB + A –> A2B
A + A –> AA;AA + B –> A2B
A + A <–> AA;AA + B –> A2B

Answer 86

A + A <–> AA;AA + B –> A2B

Question 87

A gaseous reactant is introduced in a mixed reactor of 3 litres volume at the rate of 1 litre/second. The space time is __________ seconds.
1
3
1/3
32

Answer 87

3

Question 88

The temperature dependence of reaction rate constant (K) by Arhenius law is given by
K α e^-E/RT
K α e^E/RT
K α T . e^-E/RT
K α √T . e^-E/RT

Answer 88

K α e^-E/RT

arrhenius → K α e^-E/RT
transition state → K α T . e^-E/RT
collision → K α √T . e^-E/RT

Question 89

For a __________ order chemical reaction, A + B –K–> C , the fractional conversion of reactant ‘A’ is proportional to time.
zero
first
second
third

Answer 89

zero

Question 90

Velocity of a chemical reaction
decreases with increase in temperature.
increases with increase of pressure of reactants for all reactions.
decreases with increase of reactant concentration.
none of these.

Answer 90

none of these.

Question 91

Backmixing is most predominant in
a well stirred batch reactor.
a plug-flow reactor.
a single CSTR.
CSTR’s connected in series.

Answer 91

a single CSTR.

Question 92

If helium is introduced in a reactor containing O2, SO2 and SO3 at equilibrium, so that total pressure increases while volume and temperature remains constant. In this case the dissociation of SO3 (as per Le Chatlier principle)
decreases
increases
remains unaltered
changes unpredictably.

Answer 92

decreases

Question 93

Fluidised bed reactor is characterised by
uniformity of temperature.
comparatively smaller equipment.
very small pressure drop.
absence of continuous catalyst regeneration facility.

Answer 93

uniformity of temperature.

Question 94

In which of the following gaseous phase reversible reactions, the product yield can not be increased by the application of high pressure ?
N2 + O2 <–> 2NO
PCl3 + Cl2 <–> PCl5
N + 3H2 <–> 2NH3
2SO2 + O2 <–> 2SO3

Answer 94

N2 + O2 <–> 2NO

Question 95

Space time equals the mean residence time
when the density of the reaction mixture is constant.
for large diameter tubular reactor.
for narrow diameter tubular reactor.
for CSTR.

Answer 95

when the density of the reaction mixture is constant.

Question 96

A liquid decomposes by irreversible first order kinetics and the half life period of this reaction is 8 minutes. The time required for 75% conversion of the liquid will be __________ minutes.
4
8
12
16

Answer 96

16

1st order 8 minutes 75% conversion 16 minutes

Question 97

Rate constant ‘k’ and absolute temperature ‘T’ are related by collision theory (for bimolecular) as
k ∝ T^1.5
k ∝ exp(-E/RT)
k ∝ √T
k ∝ T

Answer 97

k ∝ √T

collision √T

Question 98

The conversion for a first order liquid phase reaction. A –> B in a CSTR is 50%. If another CSTR of the same volume is connected in series, then the % conversion at the exit of the second reactor will be
60
75
90
100

Answer 98

75

Question 99

What is the dispersion number for a CSTR?
0
1
< 1
infinite

Answer 99

infinite

Question 100

Rate of a chemical reaction is independent of the concentration of the reactants for a __________ reaction.
zero order
third order
consecutive
none of these

Answer 100

zero order

Question 101

With increase in temperature, the rate constant obeying Arhenious equation
increases.
decreases.
decreases exponentially.
can either increase or decrease ; depends on the frequency factor.

Answer 101

increases.

Question 102

Bulk diffusion in catalyst pore __________ with increase in pressure.
increases
decreases
remains unchanged
increases exponentially

Answer 102

decreases

Question 103

Pick out the correct statement.
A chemical reaction accompanied by absorption of heat is called an exothermic reaction.
A chemical reaction accompanied by evolution of heat is called an endother-mic reaction.
The rate constant for a first order reaction does not change on changing the concentration units.
Chemical equilibrium state is dynamic in nature.

Answer 103

The rate constant for a first order reaction does not change on changing the concentration units.

Question 104

The concentration of A in a first order reaction, A –> B, decreases
linearly with time.
exponentially with time.
very abruptly towards the end of the reaction.
logarithmically with time.

Answer 104

exponentially with time.

Question 105

The equilibrium constant of chemical reaction __________ in the presence of catalyst.
increases
decreases
remains unaffected
can either increase or decrease (depends on the type of catalyst)

Answer 105

remains unaffected

Question 106

The order of a chemical reaction is
an experimentally determined quantity.
always equal to the total stoichiometric number of reactants.
never fractional.
none of these.

Answer 106

an experimentally determined quantity.

Question 107

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

Answer 107

equal to or more than

Question 108

In the hydrodealkylation of toluene to benzene, the following reactions occur:
C7H8 + H2 –> C6H6 + CH4
2C6H6 <–> C12H10 + H2
Toluene and hydrogen are fed to a reactor in a molar ratio 1:5.80% of the toluene gets converted and the selectivity of benzene(defined as moles of benzene formed/moles of toluene converted) is 90%. The fractional conversion of hydrogen is
0.16
0.144
0.152
0.136

Answer 108

0.144

Question 109

Catalyst is a substance, which __________ chemical reaction.
increases the speed of a
decreases the speed of a
can either increase or decrease the speed of a
alters the value of equilibrium constant in a reversible

Answer 109

can either increase or decrease the speed of a

Question 110

The residence time distribution of an ideal CSTR is
1/T exp (-t/T)
T exp (-t/T)
exp (-t/T)
1/T (-t/T)

Answer 110

exp (-t/T)

Question 111

A rise in temperature
normally tends to increase the reaction rate.
does not affect a catalysed reaction.
does not affect photo-chemical reaction rates.
all (a), (b) and (c).

Answer 111

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

Question 112

The enzyme which can catalyse the conversion of glucose to ethyl alcohol is
invertase
maltase
diastase
zymase

Answer 112

zymase

Question 113

For reaction, P + 2Q –>3R, molar rate of consumption of P is
double of that of Q.
same as that of Q.
half of that of Q.
2/3rd of that of Q.

Answer 113

half of that of Q.

Question 114

If pore diffusion is the controlling step in a solid catalysed reaction, the catalyst
porosity is very important.
porosity is of less importance.
internal surface area is utilised efficiently.
none of these.

Answer 114

porosity is of less importance.

Question 115

The conversion of a reactant, undergoing a first order reaction, at a time equal to three times the half life of the reaction is
0.875
0.5
0.425
data insufficient to calculate

Answer 115

0.875

first order three times half life 0.875

Question 116

In case of unimolecular type elementary reaction, A –K1–> B –K2–> C , plug flow reactor as compared to mixed reactor is
more
same
less
unpredictable

Answer 116

more

Question 117

What is the value of ‘n’ if the reaction rate of the chemical reaction A –> B, is proportional to CAn and it is found that the reaction rate triples, when the concentration of ‘A’ is increased 9 times ?
1/2
1/3
1/9
3

Answer 117

1/2

1/3=1/9^n,
9^n= 3,
(3)^2n= 3.

2n=1
And n=1/2.

Question 118

The first order series reaction A –k1–> B –k2–> C is conducted in a batch reactor. The initial concentrations of A, B and C (CA0, CB0, CC0 respectively) are all non-zero. The variation of CB with reaction time will not show a maximum, if
k2 CB0 > k1 CA0
k CA0 > k2.CB0
CB0 > CA0
CA0 > CB0

Answer 118

k2 CB0 > k1 CA0

Question 119

A second order reaction of the form A + B –> C is called a pseudo-first order reaction, when
CA0 = CB0
CA0 > CB0
CB0 > CA0
CB0 ≥ CB0

Answer 119

CB0 ≥ CB0

Question 120

Pick out the wrong statement.
In a first order reaction, A–> products; the reaction becomes slower as it proceeds, because the concentration of A decreases and the rate is proportional to the concentration of A.
Transition state theory approaches the problem of calculating reaction rates by concentrating on the idea of activated complexes.
According to the penetration theory, the mass transfer co-efficient decreases, if the exposure time of an eddy to the solute decreases.
If the rate of an irreversible reaction, A + B –> 2C is k.CA.CB, then the reaction is always elementary.

Answer 120

According to the penetration theory, the mass transfer co-efficient decreases, if the exposure time of an eddy to the solute decreases.

wrong According to the penetration theory…

Question 121

Effectiveness factor (E) of a catalyst pellet is defined as E = actual rate within pore of the catalyst/rate if not snowed by pore diffusion , Effectiveness factor for a first order reaction is given by (where, T = Thiele modulus)
tan hT/T
tan T/T
tan hT/tan T
none of these

Answer 121

tan hT/T

E = tan hT/T

Question 122

Inversion of cane sugar is an example of
unimolecular reaction with first order.
bimolecular reaction with second order.
bimolecular reaction with first order.
unimolecular reaction with second order.

Answer 122

bimolecular reaction with first order.

Question 123

Pick out the correct statement.
A catalyst speeds up the forward reaction but slows shown the reverse reaction.
Addition of catalyst changes the equilibrium constant.
Pressure changes do not change the equilibrium concentrations.
The composition of equilibrium is changed by catalyst.

Answer 123

Pressure changes do not change the equilibrium concentrations.

correct pressure do not change equilibrium

Question 124

In which of the following gaseous phase reactions, the equilibrium of the reaction remains unaffacted by pressure changes ?
2O3 <–> 3O2
N2 + O2 <–> 2NO
2NO2 <–> N2O4
2SO2 + O2 <–> 2SO3

Answer 124

N2 + O2 <–> 2NO

Question 125

Integral method for analysing the kinetic data is used
when the data are scattered.
for testing specific mechanisms with simple rate expressions.
both (a) and (b).
none of these.

Answer 125

both (a) and (b).

Question 126

The rate of a gas phase reaction is given by K . CA . CB. If the volume of the reaction vessel is reduced to l/4th of its initial volume, then the reaction rate compared to the original rate will be __________ times.
4
16
8
2

Answer 126

16

Question 127

Rate of a chemical reaction is not affected by the
catalyst.
temperature.
reactant’s concentration.
number of molecules of reactants taking part in the reaction.

Answer 127

number of molecules of reactants taking part in the reaction.

Question 128

Overall rate of reaction in a heterogenous catalytic reaction depends upon the mass and energy transfer from the fluid to solid surface and its rate of reaction is usually __________ the concentration of catalyst, if it does not entail a chain mechanism.
proportional to
independent of
inversely proportional to
proportional to the square of

Answer 128

proportional to

Question 129

__________ resistance is not involved in the combustion of a carbon particle.
Gas film
Ash
Chemical reaction
none of these

Answer 129

Ash

Question 130

In an ideal P.F.R. at steady state conditions
the composition of reactants remains constant along a flow path.
the conversion of the reactant varies from point to point along a flow path.
there is no lateral mixing of fluid.
there may be diffusion along the flow path.

Answer 130

the conversion of the reactant varies from point to point along a flow path.

Question 131

B.E.T. method of finding out surface area of a catalyst, uses the extension of __________ isotherm.
Langmuir
Freundlich
Tempkin
none of these

Answer 131

Langmuir

Question 132

In a chemical reaction, repesented by, A –k–> B , it is observed that the
(i) rate of reaction increases by a factor of 4 on doubling the concentration of the reactant.
(ii) rate of reaction increases by a factor of 9 on trebling the concentration of the reactant.
Then the rate of the reaction is proportional to(where, CA = contentration of the reactant)
CA
CA^2
CA^3
CA^4

Answer 132

CA^2

Question 133

Which of the following holds good for an elementary reaction, X + 2Y –k1–> 3Z ?
The rate of disappearance of ‘Y’ is equal to the rate of appearance of ‘Z’.
The rate of disappearance of ‘Y’ is equal to the rate of disappearance of ‘X’.
Three times the rate of disappearance of ‘X’ is equal to the rate of appearance of ‘Z’.
The rate of disappearance of ‘X’ is equal to the rate of appearance of ‘Z’.

Answer 133

Three times the rate of disappearance of ‘X’ is equal to the rate of appearance of ‘Z’.

Question 134

An example of autothermal reactor operation is
sulphur dioxide oxidation
ethylene oxidation
benzene oxidation
ammonia synthesis

Answer 134

ethylene oxidation

Question 135

For a packed bed reactor; the presence of a long tail in the residence time distribution curve is an indication of
ideal plug flow
bypass
dead zone
chanelling

Answer 135

dead zone

long tail - dead zone

Question 136

Space time in flow reactor is
usually equal to the residence time.
the reciprocal of the space velocity.
a measure of its capacity.
both (a) and (b).

Answer 136

both (a) and (b).

Question 137

For a first order isothermal chemical reaction in a porous catalyst, the effectiveness factor is 0.3. The effectiveness factor will increase if the
catalyst size is reduced or the catalyst diffusivity is reduced.
catalyst size is reduced or the catalyst diffusivity is increased.
catalyst size is increased or the catalyst diffusivity is reduced.
catalyst size is increased or the catalyst diffusivity is increased.

Answer 137

catalyst size is reduced or the catalyst diffusivity is increased.

Question 138

Cold shot cooling is only practical when the feed temperature is __________ than the reaction temperature.
higher
much higher
lower
much lower

Answer 138

much lower

Question 139

The preferred reacting system for oxidation of o-xylene to phthalic anhydride is
jacketted liquid phase CSTR.
jacketted steam heated multitubular reactor.
multitubular reactor with cooling.
multistage multitubular reactor with interstage cooling.

Answer 139

jacketted liquid phase CSTR.

Question 140

The effectiveness factor for large value of Thiele modulus (L.sqrt(K/D1)) of a solid catalysed first order reaction is equal to (where, L = length of the reactor, cm, D1 = diffusion co-efficient, cm2/second)
L(sqrt(K/D1))
1/L(sqrt(K/D1))
1
infinite

Answer 140

1/L(sqrt(K/D1))

Question 141

A first order reaction A B occurs in an isothermal porous catalyst pellet of spherical shape. If the concentration of A at the centre of the pellet is much less than at the external surface, the process is limited by
diffusion within the pellet.
reaction.
external mass transfer.
none of the above.

Answer 141

diffusion within the pellet.

Question 142

Following isothermal kinetic data are obtained in a basket type of mixed flow reactor for a porous catalyst. Determine the role of pore diffusion and external mass transfer processes.
kinetic data table
Strong pore diffusion control and mass transfer not controlling.
Both pore diffusion and mass transfer not controlling.
Both pore diffusion and mass transfer controlling.
Mass transfer controlling.

Answer 142

Strong pore diffusion control and mass transfer not controlling.