Chemical Reaction MCQs – Latest Chemical Engineering MCQs
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Latest Chemical Engineering MCQs
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Latest Chemical Reaction Mcqs
The most occurred mcqs of Chemical Reaction in past papers. Past papers of Chemical Reaction Mcqs. Past papers of Chemical Reaction Mcqs . Mcqs are the necessary part of any competitive / job related exams. The Mcqs having specific numbers in any written test. It is therefore everyone have to learn / remember the related Chemical Reaction Mcqs. The Important series of Chemical Reaction Mcqs are given below:
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 ?
A. Less than
B. More than
C. Same as
D. Data insufficient; can’t be predicted
The first order series reaction as shown in the bellow figure 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___________________?
A. k2 CB0 > k1 CA0
B. CB0 > CA0
C. k CA0 > k2.CB0
D. CA0 > CB0
Participation of _______________ is involved in the occurrence of a chemical reaction?
A. Neutrons
B. Protons
C. Electrons
D. None of these
A photochemical reaction is _______________ light?
A. Initiated by
B. Catalysed by
C. Accompanied with emission of
D. Used to convert heat energy into
The value of ‘n’ for a chemical reaction A → B, whose reaction rate is → CA n, will be _______________ if the rate of the reaction increases by a factor of 8, when the concentration of is doubled?
A. 1
B. 0
C. 2
D. 3
________________ resistance is not involved in the combustion of a carbon particle?
A. Chemical reaction
B. Ash
C. Gas film
D. None of these
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_____________________?
A. Equal in size
B. Of such size that the ratio of their volumes is < 5
C. Of different sizes
D. None of these
An example of autothermal reactor operation is______________________?
A. Benzene oxidation
B. Ethylene oxidation
C. Sulphur dioxide oxidation
D. Ammonia synthesis
Brunauer, 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 ?
A. 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
B. There is no dynamic equilibrium between successive layer
C. Langmuir’s assumption applies to every adsorbed layer
D. None of these
Volume change for unimolecular type first order reaction as shown in the bellow figure, increases _____________ with time?
A. Parabolically
B. Exponentially
C. Linearly
D. Logarithmically
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___________________?
A. Less
B. More
C. Same
D. Either A. or B., depends on other factors
In a zero order reaction, reactants concentration does not change with time and the_________________?
A. Time for half change is half the time taken for completion of the reaction
B. Reaction rate is trebled when the initial concentration is trebled
C. Time for completion of the reaction is independent of the initial concentration
D. Time for half change is independent of the initial concentration
Variables affecting the rate of homogeneous reactions are___________________?
A. Temperature and composition only
B. Pressure and temperature only
C. Pressure and composition only
D. Pressure, temperature and composition
If a solid-gas non-catalytic reaction occurs at very high temperature, the rate controlling step is the ________________ diffusion?
A. Film
B. Pore
C. Ash layer
D. None of these
The half life period ‘t’ of a zero order reaction as shown in the bellow figure, is equal to_________________?
A. CA0/2K
B. 0.693/K
C. CA0/K
D. 1/K
Semibatch reactor is preferred, when a/an__________________?
A. Undesirable side reaction (at high concentration of one of the reactants) is to be avoided
B. A highly exothermic reaction is to be controlled
C. A gas is to be reacted with liquid (e.g. hydrogenation of fat)
D. All A., B., and C.
In an exothermic reaction, the energy of the reacting substances as compared to that of products is____________________?
A. More
B. Same
C. Less
D. Either A. or B., depends on order of reaction
B.E.T. method can be used to determine the ___________________ of a porous catalyst?
A. Pore volume
B. Solid density
C. Surface area
D. All A., B. and C.
On application of pressure to the equilibrium system, ice ⇌ water; which of the following phenomenon will occur ?
A. More ice will be formed
B. Equilibrium will not be attained
C. Water will evaporate
D. More water will be formed
Rate of a chemical reaction is not affected by the____________________?
A. Temperature
B. Catalyst
C. Reactant’s concentration
D. Number of molecules of reactants taking part in the reaction
Batch process is preferred over continuous process, when the___________________?
A. Sales demand of product is not steady
B. Product yields and quality cannot be achieved in continuous process, because of long residence time
C. Same equipment cannot be used for several processes of the same nature
D. All A., B. & C.
For a first order isothermal chemical reaction in a porous catalyst, the effectiveness factor is 0.3. The effectiveness factor will increase if the____________________?
A. Catalyst size is increased or the catalyst diffusivity is reduced
B. Catalyst size is reduced or the catalyst diffusivity is increased
C. Catalyst size is reduced or the catalyst diffusivity is reduced
D. Catalyst size is increased or the catalyst diffusivity is increased
A second order liquid phase reaction, A → B, is carried out in a mixed flow reactor operated in semi batch mode (no exit stream). The reactant A at concentration CAF is fed to the reactor at a volumetric flow rate of F. The volume of the reacting mixture is V and the density of the liquid mixture is constant. The mass balance for A is_______________________?
A. d(VCA)/dt = F (CAF – CA) – kCA2V
B. d(VCA)/dt = -F (CAF – CA) – kCA2V
C. d(VCA)/dt = -FCA – kCA2V
D. d(VCA)/dt = FCAF – kCA2V
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 ?
A. Strong pore diffusion control and mass transfer not controlling
B. Both pore diffusion and mass transfer controlling
C. Both pore diffusion and mass transfer not controlling
D. Mass transfer controlling
The equilibrium constant of a catalytic chemical reaction _______________ due to the presence of a catalyst. ?
A. Decreases
B. Increases
C. Remain unaffected
D. Unpredictable from the data
_____________ gas is normally employed in B.E.T. method of finding out the surface area of catalyst?
A. N2
B. CO2
C. H2
D. He
Catalyst is a substance, which ________________ chemical reaction?
A. Decreases the speed of a
B. Increases the speed of a
C. Can either increase or decrease the speed of a
D. Alters the value of equilibrium constant in a reversible
What is the dispersion number for a CSTR ?
A. 1
B. 0
C. < 1
D. ∞
The rate constant of a chemical reaction increases by increasing the______________________?
A. Temperature
B. Reactant’s concentration
C. Pressure
D. None of these
Arrhenius equation shows the variation of ___________________ with temperature?
A. Energy of activation
B. Rate constant
C. Reaction rate
D. Frequency factor
The rate of the chemical reaction A → B doubles as the concentration of A i.e.., CA is doubled. If rate of reaction is proportional to CA n, then what is the value of n for this reaction ?
A. 0.5
B. 0
C. 1
D. 2
In case of calcination of limestone, CaCO3 CaO + CO2, the addition of more of CaO will result in _______________ in the concentration of CO2?
A. No change
B. Decrease
C. Increase
D. Unpredictable from the data
Exposure of a photographic plate to produce a latent image is an example of _______________ reaction?
A. Very slow
B. Photochemical
C. Very fast
D. Both B. and C.
Knudsen diffusion is directly proportional to _____________________?
A. 1/√T
B. √T
C. T
D. T2
In a chemical reaction, represented by as shown in the bellow figure, 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 = concentration of the reactant)_____________________?
A. CA
B. CA2
C. CA4
D. CA3
Chemical Heat Transfer Mcqs
Mean residence time is equal to the space time, when_________________?
A. There is no change in number of moles in gaseous reaction
B. The temperature, pressure and the density of reaction mixture remains constant throughout the reactor
C. The feed rate is measured at temperature and pressure in the reactor
D. All A., B. and C.
The following gas phase reaction is taking place in a plug flow reactor. A stoichiometric mixture of A and B at 300 K is fed to the reactor. At 1 m along the length of the reactor, the temperature is 360 K. The pressure drop is negligible and an ideal gas behaviour can be assumed. Identify the correct expression relating the concentration of A at the inlet (CA0), concentration of A at 1m (CA) and the corresponding conversion of A (X) ?
A. CA = 1.2 CA0 (1 – X)/(1 – 0.5X)
B. CA = 1.2 CA0 (1 – X)/(1 – 0.33X)
C. CA = 0.83 CA0 (1 – X)/(1 – 0.33X)
D. CA = 0.83 CA0 (1 – X)/(1 – 0.5X)
A catalyst in a chemical reaction____________________?
A. Alters the reaction mechanism
B. Decreases the activation energy
C. Increases the frequency of collisions of reacting species
D. All A., B. and C.
An irreversible aqueous phase reaction, A + B → P, is carried out in an adiabatic mixed flow reactor. A feed containing 4kmole/m3 of each A and B enters the reactor at 8m3 /hr. If the temperature of the exit stream is never to exceed 390 K, what is the maximum inlet feed temperature allowed? Data: Heat of reaction = – 50 kJ/mole Density of the reacting mixture = 1000kg/m3 Specific heat of reacting mixture = 2kJ/kg.K The above data can be assumed to be independent of temperature and composition?
A. 390
B. 290
C. 190
D. 490
The rate expression for a heterogeneous 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 >> (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) ?
A. E + ΔHA
B. E
C. E + ΔHA – ΔHR)
D. ΔHA + ΔHR
Which of the following fixes the volume of a batch reactor for a particular conversion and production rate ?
A. Rate constant
B. Operating conditions (e.g. pressure and temperature)
C. Density of mixture
D. None of these
Limiting reactant in a chemical reaction decides the____________________?
A. Reaction speed
B. Conversion
C. Rate constant
D. Equilibrium constant
The exit age distribution curve E(t) for an ideal CSTR with the average residence time, η, is given by__________________?
A. 1 – e-t/η
B. e-t/η/η
C. e-t/η
D. 1 – (e-t/η/η)
What is the value of ‘n’ if the reaction rate of the chemical reaction A → B, is proportional to CA n and it is found that the reaction rate triples, when the concentration of ‘A’ is increased 9 times ?
A. 1/2
B. 1/9
C. 1/3
D. 3
For all positive reaction orders for a particular duty ?
A. Mixed reactor is always larger than the plug-flow reactor
B. Ratio of the volume of the mixed reactor to that of the plug-flow reactor decreases with order
C. Density variation during reaction affects design
D. Reactor size is independent of the type of flow
In which of the following gaseous phase reactions, the equilibrium of the reaction remains unaffected by pressure changes ?
A. 2NO2 ⇌ N2O4
B. N2 + O2 ⇌ 2NO
C. 2O3 ⇌ 3O2
D. 2SO2 + O2 ⇌ 2SO3
Non-catalytic fluid-solid reactions are represented by _______________ model?
A. Unreacted core
B. Continuous reaction
C. Both A. and B.
D. Neither A. and B.
Which of the following holds good for an elementary reaction as shown in the bellow figure ?
A. The rate of disappearance of ‘X’ is equal to the rate of appearance of ‘Z’
B. The rate of disappearance of ‘Y’ is equal to the rate of disappearance of ‘X’
C. Three times the rate of disappearance of ‘X’ is equal to the rate of appearance of ‘Z’
D. The rate of disappearance of ‘Y’ is equal to the rate of appearance of ‘Z’
The exit age distribution of fluid leaving a vessel is used to know the__________________?
A. Reaction mechanism
B. Activation energies of a reaction
C. Extent of non-ideal flow in the vessel
D. None of these
The equilibrium constant ‘K’ of a chemical reaction depends on_________________?
A. Temperature only
B. Temperature and pressure
C. Pressure only
D. Ratio of reactants
With increase in temperature, the rate constant obeying Arrhenius equation____________________?
A. Decreases
B. Increases
C. Decreases exponentially
D. Can either increase or decrease; depends on the frequency factor
For a homogeneous reaction of nth order, the dimension of the rate constant is given by_________________?
A. (Concentration)n – 1/(time)
B. (Concentration)1 – n/(time)
C. 1/(time)n
D. None of these
A catalyst promoter_________________?
A. Improves the activity of a catalyst
B. Itself has very high activity
C. Acts as a catalyst support
D. All A., B. and C.
The vessel dispersion number (D/μL) for plug flow is_________________?
A. 0
B. 750
C. 500
D. ∞
The rate constant of a reaction is a function of the ___________________?
A. Extent of reaction
B. Temperature of the system
C. Time of reaction
D. Initial concentration of the reactants
Cold shot cooling is only practical when the feed temperature is ______________ than the reaction temperature?
A. Much higher
B. Higher
C. Lower
D. Much lower
Autocatalytic reactions are best carried out in a_________________?
A. CSTR in series
B. CSTR
C. Plug flow reactor
D. Recycle reactor
Bulk diffusion in catalyst pore _______________ with increase in pressure?
A. Remains unchanged
B. Decreases
C. Increases
D. Increases exponentially
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 ?
A. 0.152
B. 0.338
C. 0.253
D. 0.637
The extent of a reaction is ___________________?
A. Dimensionless
B. Different for reactants and products
C. Depends on the stoichiometric co-efficient
D. All of the above
Arrhenius equation represents graphically the variation between the ______________ and temperature?
A. Frequency factor
B. Rate of reaction
C. Rate constant
D. Activation energy
For a heterogeneous catalytic reaction, A + B → C, with equimole feed of A and B, the initial rate – rA0 is invariant with total pressure. The rate controlling step is______________________?
A. Surface Kc/(1 + TS) reaction between absorbed A and B in the gas phase
B. Surface reaction between A in the gas phase and absorbed B
C. Surface reaction between absorbed A and absorbed B
D. Desorption of C
The fractional volume change between no conversion and complete conversion, for the isothermal gas phase reaction, 2A → R, is___________________?
A. 1
B. -0.5
C. 0.5
D. 1.5
Half life period of decomposition of a liquid ‘A’ by irreversible first order reaction is 12 minutes. The time required for 75% conversion of ‘A’ is _____________ minutes?
A. 6
B. 24
C. 18
D. 12
The irreversible reaction, X → Y, is the special case of the reversible reaction, X ⇌ Y, in which the _____________________?
A. Concentration of ‘A’ at equilibrium is zero
B. Fractional conversion of ‘A’ at equilibrium is unity
C. Equilibrium constant is infinite
D. All A., B. and C.
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_______________?
A. CSTR of volume V/X
B. PFR of volume V
C. CSTR of volume V
D. PFR of volume V/X
Fractional conversion _________________ for an exothermic reversible chemical reaction, when the temperature is maximum?
A. Remains unchanged
B. Increases
C. Decreases
D. Unpredictable from the data
Chemical Engineering Basics Mcqs
Overall rate of reaction in a heterogeneous 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?
A. Proportional to
B. Inversely proportional to
C. Independent of
D. Proportional to the square of
For a packed bed reactor; the presence of a long tail in the residence time distribution curve is an indication of ?
A. Bypass
B. Ideal plug flow
C. Dead zone
D. Channelling
The use of space time is preferred over the mean residence time in the design of a/an____________________?
A. Slurry reactor
B. Ideal tubular-flow reactor
C. Batch reactor
D. CSTR
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__________________?
A. Diffusion within the pellet
B. External mass transfer
C. Reaction
D. None of the above
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?
A. 6
B. 4
C. 3
D. 10
The concentration of A in a first order reaction, A → B, decreases_____________________?
A. Logarithmically with time
B. Exponentially with time
C. Very abruptly towards the end of the reaction
D. Linearly with time
‘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________________?
A. V.n
B. V
C. V/n
D. 1/V
Half life period of a chemical reaction is proportional to CA0 -1, if the reaction is of _______________ order?
A. Zero
B. First
C. Second
D. Third
B.E.T. method of finding out surface area of a catalyst, uses the extension of _________________ isotherm?
A. Langmuir
B. Tempkin
C. Freundlich
D. None of these
Vegetable oils are hydrogenated in a _______________ reactor?
A. Slurry
B. Homogeneous catalytic
C. Plug flow
D. None of these
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_______________________?
A. 0.152
B. 0.144
C. 0.16
D. 0.136
Promoter_____________________?0
A. Alters the position of equilibrium in a reversible reaction
B. Initiates a chemical reaction and is a catalyst by itself
C. Increases the number of active centres by increasing the unevenness of catalyst surface and by
creating discontinuities in the crystals
D. All A., B. and C.
In an ideal P.F.R. at steady state conditions ___________________?
A. There is no lateral mixing of fluid
B. The conversion of the reactant varies from point to point along a flow path
C. The composition of reactants remains constant along a flow path
D. There may be diffusion along the flow path
The reaction rate almost gets doubled for 10°C rise in temperature. This is due to the fact that the_________________?
A. Collision frequency increases
B. Fraction of molecules having threshold energy increases
C. Increased temperature reduces the activation energy
D. Value of threshold energy decreases
The order of a chemical reaction is__________________?
A. An experimentally determined quantity
B. Never fractional
C. Always equal to the total stoichiometric number of reactants
D. None of these
The rate of reaction does not decrease appreciably as the reaction proceeds in case of ______________ reactions?
A. Autocatalytic
B. Endothermic
C. Exothermic
D. Autothermal
Space time in flow reactor is____________________?
A. The reciprocal of the space velocity
B. Usually equal to the residence time
C. A measure of its capacity
D. Both A. and B.
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__________________?
A. Higher in P.F. reactor
B. Same in both the reactors
C. Higher in CSTR
D. Data insufficient; can’t be predicted
If pore diffusion is the controlling step in a solid catalysed reaction, the catalyst___________________?
A. Internal surface area is utilised efficiently
B. Porosity is of less importance
C. Porosity is very important
D. None of these
The energy of activation of a chemical reaction ?
A. Varies as fifth power of the temperature
B. Is the minimum energy which the molecules must have before the reaction can take place
C. Is same as heat of reaction at constant pressure
D. Both B. and C.
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 ___________________?
A. > 1
B. 1
C. ∞
D. ≥ 1
Which of the following does not produce a change in the value of rate constant of a reaction ?
A. Temperature
B. Pressure
C. Concentration and catalyst
D. None of these
The dispersion number of perfect mixed flow is__________________?
A. > 150
B. 0
C. ∞
D. < 2100
In autocatalytic reactions ?
A. Catalysts have very high selectivity
B. One of the products acts as a catalyst
C. One of the reactants acts as a catalyst
D. No catalyst is used
For series reaction, the relative yield__________________?
A. Decreases with increasing conversion
B. Statement in A. is wrong
C. Is always greater for plug-flow reactor than for the single CSTR of the same volume
D. Both A. and C. hold good
The rate of a homogeneous reaction is a function of__________________?
A. Temperature and composition only
B. Temperature and pressure only
C. Pressure and composition only
D. All temperature, pressure and composition
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_______________________?
A. 1
B. 0
C. 2
D. 3
In case of a P.F.R., there__________________________?
A. Should not be any mixing along the flow path
B. May be lateral mixing of fluid
C. Both A. and B.
D. Neither A. nor B.
For an ideal mixed flow reactor (CSTR), the exit age distribution E(t) is given by __________________?
A. A step function
B. A Dirac delta function
C. A ramp function
D. None of the above
An irreversible first order reaction is being carried out in a CSTR and PFR of same volume. The liquid flow rates are same. The relative conversion will__________________?
A. Be same in both cases
B. Be more in PFR than in CSTR
C. Be more in CSTR than in PFR
D. Depend on the temperature
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 ?
A. 100
B. 200
C. 150
D. 225
The first order gas phase reaction as shown in the bellow figure is conducted isothermally in batch mode. The rate of change of conversion with time is given by________________?
A. dXA/dt = k1 (1 – XA) (1 + 0.5XA)
B. dXA/dt = k1 (1 – XA)2 (1 + 2XA)
C. dXA/dt = k1 (1 – XA)
D. dXA/dt = k1 (1 – XA)/(1 + XA)
Fluid flow in a real packed bed can be approximated as ________________ model?
A. Mixed flow
B. Dispersion
C. Plug flow
D. Tank in series