The rate constant of a chemical reaction decreases by decreasing the
1.
pressure
2.
concentration of reactants
3.
temperature
4.
duration of reaction
Which of the following is the most suitable for very high pressure gas phase reaction ?
1.
Stirred tank reactor
2.
Batch reactor
3.
Tubular flow reactor
4.
Fluidised bed reactor
__________ is the response curve for a step input input signal from a reactor.
1.
C-curve
2.
none of these
3.
I-curve
4.
S-curve
A catalyst
1.
initiates a reaction.
2.
lowers the activation energy of reacting molecules.
3.
is capable of reacting with any one of the reactants.
4.
can not be recovered chemically unchanged at the end of a chemical reaction.
For high conversion in a highly exothermic solid catalysed reaction, use a __________ bed reactor.
1.
fixed bed reactor followed by a fluidised
2.
fluidised bed reactor followed by a fixed
3.
fluidised
4.
fixed
For every 10°C rise in temperature, the rate of chemical reaction doubles. When the t emperature is increased from 30 to 70°C, the rate of reaction increases __________ times.
1.
8
2.
32
3.
12
4.
16
A first order reaction requires two equal sized CSTR. The conversion is
1.
less when they are connected in series.
2.
more when they are connected in series.
3.
same whether they are connected in series or in parallel.
4.
more when they are connected in parallel.
In case of physical adsorption, the heat of adsorption is of the order of __________ kcal/kg.mole.
1.
1000
2.
100
3.
10000
4.
100000
A reactor is generally termed as an autoclave, when it is a
1.
high pressure batch reactor.
2.
atmospheric pressure tank reactor.
3.
high pressure tubular reactor.
4.
atmospheric pressure CSTR.
Which of the following will give maximum gas conversion ?
1.
Fluidised bed reactor.
2.
Fixed bed reactor.
3.
Semi-fluidised bed reactor.
4.
Plug-flow catalytic reactor.
__________ explains the mechanism of catalysis.
1.
Collision theory
2.
None of these
3.
Thermodynamics
4.
Activated complex theory
The most unsuitable reactor for carrying out reactions in which high reactant concentration favours high yields is
1.
backmix reactor
2.
plug flow reactor
3.
series of CSTR
4.
PFR in series
From among the following, choose one which is not an exothermic process.
1.
Methanol synthesis
2.
Catalytic cracking
3.
Oxidation of sulphur
4.
Ammonia synthesis
The reaction between oxygen and organic material is a/an __________ reaction.
1.
biochemical
2.
endothermic
3.
photochemical
4.
exothermic
A batch reactor is suitable for
1.
liquid phase reactions.
2.
achieving cent percent conversion of reactants into products.
3.
large scale gaseous phase reactions.
4.
obtaining uniform polymerisation products in highly exothermic reactions.
With decrease in temperature, the equilibrium conversion of a reversible endother-mic reaction
1.
decreases
2.
remains unaffected
3.
increases
4.
increases linearly with temperature
In an exothermic chemical reaction, the reactants compared to the products have
1.
higher temperature
2.
more energy
3.
less energy
4.
same energy.
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
1.
decreases
2.
is at the highest allowable temperature throughout.
3.
first increases and then decreases.
4.
increases
The rate constant of a chemical reaction increases by 100 times when the te mperature is increased from 400 °K to 500 °K. Assuming transition state theory is valid, the value of E/R is
1.
8764°K
2.
8987°K
3.
9210°K
4.
8621°K
For a heterogeneous catalytic reaction
1.
the catalyst does not form an intermediate complex with the reactant.
2.
the surface of the catalyst does not play an important role during reaction.
3.
a relatively small amount of catalyst can cause the conversion of large amount of reactants
which does not mean that catalyst concentration is important.
4.
free energy of activation is lowered in the presence of catalyst, which remains unchanged at the
end of reaction. The reason why a catalyst increases the rate of reaction is that, it
1.
decreases the molecular collision diameter.
2.
increases the activation energy.
3.
decreases the energy barrier for reaction.
4.
none of these.
A reaction in which one of the products of reaction acts as a catalyst is called a/an __________ reaction.
1.
photochemical
2.
autocatalytic
3.
catalytic
4.
none of these
BET apparatus
1.
is made entirely of stainless steel.
2.
measures the catalyst surface area directly.
3.
operates at very high pressure.
4.
none of these.
The rate constant of a first order reaction depends on the
1.
concentration of the product.
2.
time
3.
concentration of the reactant.
4.
temperature.
Pick out the correct statement.
1.
A catalyst lowers the activation energy of the reacting molecules.
2.
A catalyst initiates a chemical reaction.
3.
A catalyst can not be recovered chemi cally unchanged at the end of the chemical reaction.
4.
In catalytic reactions, the catalyst reacts with the reactants.
The dimensions of rate constant for reaction 3A B are (l/gm mole)/min. Therefore the reaction order is
1.
0
2.
1
3.
3
4.
2
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.
2.24
2.
2.5
3.
1.6
4.
2
Pick out the wrong statement.
1.
The vessel dispersion number (D/UL) for plug flow and mixed flow approaches zero and
infinity respectively.
2. Mixed reactor is always smaller than the plug flow reactor for all positive reaction orders for a particular duty. 3.
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.
4. In an ideal tubular flow reactor, mixing takes place in radial direction and there is no mixing in logitudinal direction.
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.
1.
second
2.
three
3.
any
4.
first
Conversion increases with increase in temperature in case of a an __________ reaction.
1.
autocatalytic
2.
irreversible
3.
reversible endothermic
4.
reversible exothermic
Pick out the correct statement
1.
Chemical equilibrium is a static state.
2.
A chemical reaction occurs when the energy of the reacting molecule is less than the activation
energy of the reaction.
3.
Reactions with high activation energies are very temperature sensitive.
4.
A photochemical reaction is catalysed by light.
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
1.
0
2.
2
3.
1
4.
3
__________ is the controlling step in a highly temperature sensitive fluid-solid non-catalytic reaction.
1.
Ash diffusion
2.
Gas film diffusion
3.
Chemical reaction
4.
none of these
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
2.
<1
3.
1
4.
0
An autothermal reactor is
1.
most suitable for a second order reaction.
2.
most suitable for a reversible reaction.
3.
completely self-supporting in its thermal energy requirements.
4.
isothermal in nature.
Radioactive decay follows __________ order kinetics.
1.
second
2.
zero
3.
first
4.
third
The excess energy of reactants in a chemical reaction required to dissociate into products is termed as the __________ energy.
1.
activation
2.
potential
3.
binding
4.
threshold
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
1.
∞
2.
0
3.
1
4.
>1
The increase in the rate of reaction with temperature is due t o
1.
increase in the number of effective collisions.
2.
increase in the average kinetic energy of the reacting molecules.
3.
decrease in activation energy.
4.
none of these.
Which of the following will favour the reverse reaction in a chemical equilibrium reaction ?
1.
Increasing the concentration of one of the reactants.
2.
Increasing the concentration of one or more of the products.
3.
None of these.
4.
Removal of at least one of the products at regular interval.
In a/an __________ reactor, there is exchange of heat with the surroundings with sizeable temperature variation.
1.
adiabatic
2.
isothermal
3.
non-adiabatic
4.
none of these.
‘Unreacted core model’ represents the reaction involving
1.
roasting of sulphide ores.
2.
manufacture of carbon disulphide from elements.
3.
none of these.
4.
combustion of coal particles.
A batch reactor is characterised by
1.
variation in extent of reaction and properties of the reaction mixture with time.
2.
variation in reactor volume.
3.
very low conversion.
4.
constant residence time.
In a reversible chemical reaction having two reactants in equilibrium, if the concentration of the reactants are doubled, then the equilibrium constant will
1.
remain the same
2.
be halved
3.
also be. doubled
4.
become one fourth
Pick out the correct statement.
1.
The dispersion number for a reactor/vessel is uL/D.
2.
A lower temperature favours the reaction of lower activation energy.
3.
The rate controlling step in a reaction involving many steps is the fastetst step.
4. Pore volume and porosity of a catalyst is measured by Brunaver-Emmet-Teller (BET) technique.
Rate determining step in a reaction consisting of a number of steps in series is the __________ step.
1.
data insufficient; can't be predicted
2.
fastest
3.
slowest
4.
intermediate
The catalytic activity of enzymes is due to their capacity to lower the __________ energy.
1.
potential
2.
none of these
3.
activation
4.
kinetic
For nearly isothermal operation involving large reaction time in a liquid- phase reaction, the most suitable reactor is a __________ reactor.
1.
stirred tank
2.
tubular flow
3.
batch
4.
fixed bed
Which of the following is an independent variable for a batch tank reactor with uniform concentration and temperature ?
1.
None of these
2.
Time
3.
Diameter of the reactor
4.
Useful volume of the tank
The equilibrium constant of a catalytic chemical reaction __________ due to the presence of a catalyst.
1.
increases
2.
remains unaffected
3.
decreases
4.
unpredictable from the data
When all the limiting reactant is consumed in the reaction, the operational yield __________ the relative yield.
1.
is greater than
2.
is smaller than
3.
equals
4.
can be either greater or smaller than (depends on the type of reaction)
Which of the following is not a chemical step in a fluid solid catalytic reaction ?
1.
Surface chemical reaction
2.
Desorption
3.
None of these
4.
Adsorption
Pick out the wrong statement.
1.
In a batch reactor, which is exclusively used for liquid phase reactions; temperature pressure
and composition may vary with time.
2.
In a semi-batch reactor, one reactant is charged batchwise, while the other reactant is fed
continuously.
3.
In a continuous flow reactor, uniform concentration can not be maintained throughout the
vessel even in a well agitated system.
4.
In a continuous flow reactor, both the reactants and the products flow out continuously.
The rate constant of a chemical reaction increases by increasing the
1.
reactant's concentration
2.
temperature
3.
pressure
4.
none of these
In case of __________ reactions, the reaction rate does not decrease appreciably as the reaction proceeds.
1.
parallel
2.
series
3.
auto catalytic
4.
catalytic
The units of frequency factor in Arhenious equation
1.
are the same as those of the rate constant.
2.
depend on temperature, pressure etc. of the reaction.
3.
depend on the order of the reaction.
4.
are cycles per unit time.
When a catalyst increases the rate of forward reaction, the value of rate constant
1.
decreases
2.
increases
3.
remain same
4.
becomes infinite
If a solid-gas non-catalytic reaction occurs at very high temperature, the rate controlling step is t he __________ diffusion.
1.
film
2.
ash layer
3.
pore
4.
none of these
A photochemical reaction is __________ light.
1.
initiated by
2.
used to convert heat energy into
3.
accompanied with emission of
4.
catalysed by
The rate of a chemical reaction is almost doubled for every 1 0°C rise in temperature. The rate will increase __________ times, if the temperature rises form 10 to 100°C.
1.
112
2.
256
3.
512
4.
612
Fluid flow in a real packed bed can be approximated as __________ model.
1.
mixed flow
2.
plug flow
3.
dispersion
4.
tank in series
A reaction which is catalysed by a base is catalysed by all substances which have a tendency to
1.
lose a proton
2.
gain a proton
3.
none of these
4.
gain an electron
The reaction in which one of the products of reaction acts as a catalyst is called a/an __________ reaction.
1.
biochemical
2.
catalytic
3.
photochemical
4.
autocatalytic
In autocatalytic reactions,
1.
one of the products acts as a catalyst.
2.
one of the reactants acts as a catalyst.
3.
catalysts have very high selectivity.
4.
no catalyst is used.
Pick out the wrong statement.
1.
For a second order reaction, the slope of the graph/plot between rate and (concentration) is
equal to the rate constant (k).
2.
Visible radiation provides the necessary activation energy in photochemical reactions.
3.
The order and molecularity of a complex reaction may not be the same.
4.
Molecularity of the reaction is always a whole number greater than zero.
Which of the following curves shows the effect of temperature on the extent of gas-solid adsorption at a given pressure ?
1.
Adsorption isobar
2.
Langmuir adsorption isotherm
3.
Freundlich adsorption isotherm
4.
None of these
If the rate of a chemical reaction becomes slower at a given te mperature, then the
1.
initial concentration of the reactants remains constant.
2.
entropy changes.
3.
free energy of activation is lower.
4.
free energy of activation is higher.
The catalyst in a second order reversible reaction increases the rate of the forward reaction
1.
and decreases that of backward reaction.
2.
only
3.
and backward reaction equally.
4.
to a greater extent than that of the backward reaction.
What is the order of a chemical reaction whose rate is deter-mined by the variation of one concentration term only ?
1.
third
2.
zero
3.
first
4.
second
A reaction which is catalysed by an acid is also catalysed by any substance, which has a tendency to
1.
lose an electron
2.
gain a proton.
3.
lose a proton.
4.
none of these.
For a zero order reaction, the concentration of product increases with the
1.
increase in initial concentration.
2.
total pressure.
3.
decrease in total pressure.
4.
increase of reaction time.
Catalyst carriers
1.
inhibit catalyst poisoning.
2.
increase the activity of a catalyst.
3.
provide large surface area with a small amount of active material.
4.
have very high selectivity.
A typical example of an exothermic reversible reaction conducted at high pressure in industry is
1.
reformation of methane.
2.
methanol synthesis.
3.
dehydration of ethanol.
4.
polymerisation of ethylene.
The rate at which a chemical substance reacts is proportional to its
1.
molecular weight
2.
active mass
3.
equivalent weight
4.
none of these
The half life period of a first order reaction is
1.
dependent on initial concentration of the reactants.
2.
always the same irrespective of the reaction.
3.
proportional to the initial concentration of reactants.
4.
half the specific rate constant.
Pick out the wrong statement.
1.
For studying a chemical reaction, it is desirable to monitor the reactants during initial stages
and the products during the final stages of reaction.
2.
'Hold back' is defined as the fraction of material that stays longer than the mean residence time.
3.
A batch reactor can not be used to study the kinetics of catalytic reaction.
4.
Study of non-ideal flow reactor is done experimentally by stimulus-response technique.
A plug-flow reactor is characterised by
1.
constant composition and temperature of reaction mixture.
2.
presence of axial mixing.
3.
high capacity.
4.
presence of lateral mixing.
For a tubular reactor with space time ‘τ’ and residence time ‘θ’, the following statement holds good.
1.
τ and θ are always equal.
2.
τ = θ , when the fluid density changes in the reactor.
3.
τ = θ , for an isothermic tubular reactor in which the density of the process fluid is constant.
4.
τ = θ , for a non-isothermal reactor.
For an ideal mixed flow reactor (CSTR), the exit a ge distribution E(t) is given by
1.
a dirac delta function
2.
a ramp function.
3.
a step function.
4.
none of the above
Study of chemical kinetics is the easiest in the case of __________ reactions.
1.
irreversible
2.
reversible
3.
side
4.
surface
