Chemical Reaction MCQs

Option A: For a first order consecutive reaction, a tubular flow reactor as compared to a stirred tank

Option B: For an ideal mixed reactor at steady state, the exit stream has the same composition as fluid

Option C: Plug flow reactor (PFR) is always smaller than mixed reactor for all positive reaction orders

Option D: Reaction rate does not decrease appreciably as the reaction proceeds in case of an

Correct Answer: A. For a first order consecutive reaction, a tubular flow reactor as compared to a stirred tank
reactor provides higher overall selectivity ✔

Option A: For the same conversion, the holding time required in a batch reactor, is always equal to the space time required in a PFR

Option B: Two mixed reactors of unequal size are available for producing a specified product, formed by

Option C: Arrhenius equation describing the effect of temperature on rate constant is given by,

Option D: The mechanism for the decomposition of CH3CHO into CH4 and CO in presence of I2 is:

Correct Answer: D. The mechanism for the decomposition of CH3CHO into CH4 and CO in presence of I2 is:
CH3CHO + I2 → CH3I + HI + CO; slow
CH3I + HI → CH4 + I2; fast
Then the rate of disappearance of CH3CHO is equal to K.CCH3I.CHI and acts as a catalyst ✔

Option A: A chemical reaction accompanied by absorption of heat is called an exothermic reaction

Option B: A chemical reaction accompanied by evolution of heat is called an endothermic reaction

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

Option D: Chemical equilibrium state is dynamic in nature

Correct Answer: The rate constant for a first order reaction does not change on changing the concentration units ✔

Option A: A catalyst speeds up the forward reaction but slows shown the reverse reaction

Option B: Addition of catalyst changes the equilibrium constant

Option C: Pressure changes do not change the equilibrium concentrations

Option D: The composition of equilibrium is changed by catalyst

Correct Answer: Pressure changes do not change the equilibrium concentrations ✔

Option A: A catalyst does not change AH of the reaction

Option B: A catalyst changes the equilibrium point

Option C: Law of mass action was suggested by Le-Chatelier

Option D: The difference between the energy of reactants and that of the products is the activation

Correct Answer: A catalyst does not change AH of the reaction ✔

Option A: Autocatalytic reactions are exemplified by microbial fermentation reactions

Option B: The slowest step has the greatest influence on the overall reaction rate in case of an

Option C: The fractional conversion at any time is same for both the constant as well as the variable

Option D: Hydrolysis of ester in presence of alkali or acid is a zero order reaction

Correct Answer: Hydrolysis of ester in presence of alkali or acid is a zero order reaction ✔

Option A: Visible radiation provides the necessary activation energy in photochemical reactions

Option B: The order and molecularity of a complex reaction may not be the same

Option C: For a second order reaction, the slope of the graph/plot between rate and (concentration) is

Option D: Molecularity of the reaction is always a whole number greater than zero

Correct Answer: The order and molecularity of a complex reaction may not be the same ✔

Option A: A catalyst does not alter the final position of equilibrium in a reversible reaction

Option B: A catalyst initiates a reaction

Option C: A catalyst is specific in reaction

Option D: A catalyst remains unchanged in chemical composition at the end the reaction

Correct Answer: A catalyst initiates a reaction ✔

Option A: In a first order reaction, A → products; the reaction becomes slower as it proceeds, because

Option B: Transition state theory approaches the problem of calculating reaction rates by concentrating

Option C: According to the penetration theory, the mass transfer co-efficient decreases, if the exposure

Option D: If the rate of an irreversible reaction, A + B → 2C is k.CA.CB, then the reaction is always

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

Option A: ‘Hold back’ is defined as the fraction of material that stays longer than the mean residence time

Option B: Study of non-ideal flow reactor is done experimentally by stimulus-response technique

Option C: For studying a chemical reaction, it is desirable to monitor the reactants during initial stages

Option D: A batch reactor cannot be used to study the kinetics of catalytic reaction

Correct Answer: A batch reactor cannot be used to study the kinetics of catalytic reaction ✔

Option A: The unit of space velocity is (time)-1

Option B: The space velocity of 3 hr-1 means that three reactor volumes of feed at specified conditions

Option C: The space velocity of 3 hr-1 means that one third reactor volume of feed at specified

Option D: None of these

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

Option A: In catalytic reactions, the catalyst reacts with the reactants

Option B: A catalyst initiates a chemical reaction

Option C: A catalyst lowers the activation energy of the reacting molecules

Option D: A catalyst cannot be recovered chemically unchanged at the end of the chemical reaction

Correct Answer: In catalytic reactions, the catalyst reacts with the reactants ✔

Option A: Catalytic activity of enzyme catalysed reactions which is affected by temperature, pH value &

Option B: Most of the enzyme catalysed reactions involve at least two substrates

Option C: Enzymes help in increasing the activation energy of the reaction

Option D: Equilibrium concentrations in enzyme catalysed reactions can be calculated by using the

Correct Answer: Enzymes help in increasing the activation energy of the reaction ✔

Option A: The vessel dispersion number (D/UL) for plug flow and mixed flow approaches zero and

Option B: 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

Option C: Mixed reactor is always smaller than the plug flow reactor for all positive reaction orders for a

Option D: In an ideal tubular flow reactor, mixing takes place in radial direction and there is no mixing in longitudinal direction

Correct Answer: C. Mixed reactor is always smaller than the plug flow reactor for all positive reaction orders for a
particular duty ✔

Option A: Exit age description function E. and internal age distribution function (I) are related as, E = -(dI/dθ)

Option B: Chemisorption studies are useful in the determination of catalyst surface area and pore size distribution

Option C: A higher temperature favours the reaction of higher activation energy

Option D: A catalyst increases the potential energy barrier over which the reactants must pass to form products

Correct Answer: A catalyst increases the potential energy barrier over which the reactants must pass to form products ✔

Option A: Use of different catalysts in a reversible catalytic chemical reaction does not change the

Option B: Alumina is added as a promoter to iron catalyst in ammonia synthesis reaction

Option C: Activation energy for a reaction is obtained from the intercept of the Arrhenius plot

Option D: Presence of inerts affects the equilibrium conversion of

Correct Answer: Activation energy for a reaction is obtained from the intercept of the Arrhenius plot ✔

Option A: A particular chemical reaction is more temperature sensitive at low temperatures

Option B: A very high value of equilibrium constant, K (K >> 1) indicates that the reaction is practically

Option C: The intercept of the Arrhenius plot is called the ‘activation energy’

Option D: Non-ideal flow takes place in reactors due to recycling, channeling or by creation of stagnant

Correct Answer: C. The intercept of the Arrhenius plot is called the ‘activation energy’ ✔

Option A: A lower temperature favours the reaction of lower activation energy

Option B: The dispersion number for a reactor/vessel is uL/D

Option C: The rate controlling step in a reaction involving many steps is the fastest step

Option D: Pore volume and porosity of a catalyst is measured by Brunauer-Emmett-Teller (BET)

Correct Answer: A lower temperature favours the reaction of lower activation energy ✔

Option A: In a batch reactor, which is exclusively used for liquid phase reactions; temperature pressure and composition may vary with time

Option B: In a semi-batch reactor, one reactant is charged batch wise, while the other reactant is fed continuously

Option C: In a continuous flow reactor, uniform concentration cannot be maintained throughout the vessel even in a well agitated system

Option D: In a continuous flow reactor, both the reactants and the products flow out continuously

Correct Answer: In a continuous flow reactor, uniform concentration cannot be maintained throughout the vessel even in a well agitated system ✔

Option A: The integral method of analysing kinetic data is used when the data is scattered

Option B: The differential method of analysing kinetic data requires more accurate or larger amounts of data

Option C: When the reaction rate is independent of temperature, the reaction is said to be of zero order

Option D: 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

Correct Answer: When the reaction rate is independent of temperature, the reaction is said to be of zero order ✔

Option A: Reactions with high activation energies are very temperature sensitive

Option B: Chemical equilibrium is a static state

Option C: A photochemical reaction is catalysed by light

Option D: A chemical reaction occurs when the energy of the reacting molecule is less than the activation energy of the reaction

Correct Answer: Reactions with high activation energies are very temperature sensitive ✔

Option A: Chemical reactions with high activation energy are very temperature sensitive

Option B: A flat velocity profile exists in a plug flow reactor

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

Option D: Half life of a reaction increases with increased initial concentration for reaction orders more

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

Option A: Elementary

Option B: Multiple

Option C: Autocatalytic

Option D: Non-elementary

Correct Answer: Non-elementary ✔

Option A: Is independent of temperature

Option B: Varies with temperature

Option C: Depends on the nature of the reactants

Option D: Both B. and C.

Correct Answer: D. Both B. and C. ✔

Option A: Inner catalyst core of radius R/8 does not participate in reaction

Option B: Inner catalyst core of radius R/2 does not participate in reaction

Option C: Inner catalyst core of radius 7R/8 does not participate in reaction

Option D: Effectiveness factor for a zero order reaction cannot be 7/8 as it must always be 1

Correct Answer: Inner catalyst core of radius R/8 does not participate in reaction ✔

Option A: 1

Option B: 2

Option C: 3

Option D: 4

Correct Answer: 2 ✔

Option A: Nature of the reactants

Option B: Concentration of the reactants

Option C: Temperature at which the reaction is carried

Option D: All A., B. and C.

Correct Answer: D. All A., B. and C. ✔

Option A: Methanol synthesis

Option B: Catalytic cracking

Option C: Ammonia synthesis

Option D: Oxidation of sulphur

Correct Answer: Catalytic cracking ✔

Option A: 5°C

Option B: 10°C

Option C: 20°C

Option D: 100°C

Correct Answer: 10°C ✔

Option A: Backmix reactor

Option B: Plug flow reactor

Option C: Series of CSTR

Option D: PFR in series

Correct Answer: Backmix reactor ✔

Option A: 100

Option B: 97.5

Option C: 95

Option D: 2.5

Correct Answer: 100 ✔

Option A: Pressure

Option B: Temperature

Option C: Both A. & B.

Option D: Neither A. nor B.

Correct Answer: Temperature ✔

Option A: Mixing takes place in axial direction only

Option B: Velocity of reaction can be controlled

Option C: Condition similar to plug flow reactor exists

Option D: Residence time is constant

Correct Answer: Velocity of reaction can be controlled ✔

Option A: Loss in surface area of the active component

Option B: Agglomeration of metal particles caused by thermal sintering of the solid surface

Option C: Covering of the catalytic active sites by a foreign substance

Option D: All A., B. and C.

Correct Answer: D. All A., B. and C. ✔

Option A: k ∝ e-E/RT

Option B: k ∝ T.eE/RT

Option C: k ∝ √T

Option D: k ∝ T1.5

Correct Answer: k ∝ T.eE/RT ✔

Option A: 0

Option B: 1

Option C: 2

Option D: 3

Correct Answer: 2 ✔

Option A: 1/4

Option B: 1/2

Option C: 2

Option D: 4

Correct Answer: 1/4 ✔

Option A: 0.5

Option B: 1

Option C: 2

Option D: 3

Correct Answer: 2 ✔

Option A: 0

Option B: 1

Option C: 2

Option D: 3

Correct Answer: 1 ✔

Option A: Pressure

Option B: Concentration of reactants

Option C: Temperature

Option D: Duration of reaction

Correct Answer: Temperature ✔

Option A: (CA/2)n

Option B: (½)n CA

Option C: (CA/2)1/n

Option D: (CA)1/2n

Correct Answer: (½)n CA ✔

Option A: Higher temperature

Option B: More energy

Option C: Less energy

Option D: Same energy

Correct Answer: More energy ✔

Option A: Measures the catalyst surface area directly

Option B: Operates at very high pressure

Option C: Is made entirely of stainless steel

Option D: None of these

Correct Answer: None of these ✔

Option A: 1.5 K

Option B: 2.5 K

Option C: 0.693/K

Option D: 6.93 K

Correct Answer: 0.693/K ✔

Option A: Decreases the energy barrier for reaction

Option B: Increases the activation energy

Option C: Decreases the molecular collision diameter

Option D: None of these

Correct Answer: Decreases the energy barrier for reaction ✔

Option A: Initiates a reaction

Option B: Lowers the activation energy of reacting molecules

Option C: Is capable of reacting with any one of the reactants

Option D: Cannot be recovered chemically unchanged at the end of a chemical reaction

Correct Answer: Lowers the activation energy of reacting molecules ✔

Option A: k KA pApB / (1 + KApA + KBpB)

Option B: k KAKB pApB / (1 + KApA + KBpB)

Option C: k KAKB pApB / (1 + KApA + KBpB + KCpC)

Option D: k KAKB pApB / (1 + KApA + KBpB + KCpC)2

Correct Answer: k KAKB pApB / (1 + KApA + KBpB + KCpC) ✔

Option A: Zero

Option B: One

Option C: Two

Option D: Three

Correct Answer: One ✔

Option A: Total pressure of the system

Option B: Volume of the reactor

Option C: Temperature

Option D: Initial concentration of N2 and H2

Correct Answer: Temperature ✔

Option A: Free energy of activation is lowered in the presence of catalyst, which remains unchanged at

Option B: A relatively small amount of catalyst can cause the conversion of large amount of reactants

Option C: The catalyst does not form an intermediate complex with the reactant

Option D: The surface of the catalyst does not play an important role during reaction

Correct Answer: A. Free energy of activation is lowered in the presence of catalyst, which remains unchanged at
the end of reaction ✔

Option A: 2

Option B: 4

Option C: 11

Option D: 22

Correct Answer: 11 ✔

Option A: Accompanied with emission of light

Option B: Catalysed by light

Option C: Initiated by light

Option D: All A., B. & C.

Correct Answer: Initiated by light ✔

Option A: Fixed

Option B: Fluidised bed reactor followed by a fixed

Option C: Fixed bed reactor followed by a fluidised

Option D: Fluidised

Correct Answer: Fluidised bed reactor followed by a fixed ✔

Option A: Quality & yield cannot be achieved in continuous processes, because of long residence time

Option B: Sales demand is fluctuating

Option C: Both A. & B.

Option D: Neither A. nor B.

Correct Answer: C. Both A. & B. ✔

Option A: Decreases

Option B: Increases

Option C: Is at the highest allowable temperature throughout

Option D: First increases and then decreases

Correct Answer: Is at the highest allowable temperature throughout ✔

Option A: Suitable for gas-phase reactions on commercial scale

Option B: Suitable for liquid phase reactions involving small production rate

Option C: Least expensive to operate for a given rate

Option D: Most suitable for very large production rate

Correct Answer: Suitable for liquid phase reactions involving small production rate ✔

Option A: First

Option B: Second

Option C: Third

Option D: Zero

Correct Answer: First ✔

Option A: Tank in series

Option B: Dispersion

Option C: Both A. & B.

Option D: Neither A. nor B.

Correct Answer: C. Both A. & B. ✔

Option A: It is a reversible reaction

Option B: It is an exothermic reaction

Option C: The energy of reacting molecules exceeds the activation energy by absorption of light

Option D: None of these

Correct Answer: The energy of reacting molecules exceeds the activation energy by absorption of light ✔

Option A: Achieving cent percent conversion of reactants into products

Option B: Large scale gaseous phase reactions

Option C: Liquid phase reactions

Option D: Obtaining uniform polymerisation products in highly exothermic reactions

Correct Answer: Liquid phase reactions ✔

Option A: Is same as plug-flow reactor

Option B: Is same as ideal stirred tank reactor

Option C: Employs mixing in axial direction only

Option D: Is most suitable for gas phase reaction

Correct Answer: Is same as ideal stirred tank reactor ✔

Option A: Physical

Option B: Chemical

Option C: Both A. and B.

Option D: Neither A. nor B.

Correct Answer: Chemical ✔

Option A: Both forward and backward reactions will be exothermic

Option B: Neither of the reactions will be endothermic

Option C: The combination reaction will be exothermic, while the dissociation reaction will be

Option D: The combination reaction will be endothermic, while the dissociation reaction will be

Correct Answer: C. The combination reaction will be exothermic, while the dissociation reaction will be
endothermic ✔

Option A: 100

Option B: 1000

Option C: 10000

Option D: 100000

Correct Answer: 100 ✔

Option A: Heat and mass transfer effects

Option B: Pressure

Option C: Temperature

Option D: Composition of reactant

Correct Answer: Heat and mass transfer effects ✔

Option A: Half life period is directly proportion to the initial concentration of the reactants

Option B: Plot of products concentration with time is a straight line through the origin

Option C: Products concentration increases linearly with time

Option D: All A., B. and C.

Correct Answer: D. All A., B. and C. ✔

Option A: Multiple proportion

Option B: Conservation of mass

Option C: Constant proportion

Option D: None of these

Correct Answer: Conservation of mass ✔

Option A: S-curve

Option B: C-curve

Option C: I-curve

Option D: None of these

Correct Answer: C-curve ✔

Option A: First

Option B: Second

Option C: Third

Option D: Any

Correct Answer: Any ✔

Option A: Temperature is very high

Option B: Reactant’s concentration is very high

Option C: Reactant’s concentration is very low

Option D: Reaction rate is independent of the reactant’s concentration

Correct Answer: Temperature is very high ✔

Option A: Solid state only

Option B: Liquid state only

Option C: Solutions

Option D: Any state

Correct Answer: Solutions ✔

Option A: Decreases

Option B: Increases

Option C: Remain unaffected

Option D: Increases linearly with temperature

Correct Answer: Decreases ✔

Option A: Ions

Option B: Masses

Option C: Atoms

Option D: Both B. & C.

Correct Answer: D. Both B. & C. ✔

Option A: Hydrogenation of oils

Option B: Gas phase oxidation of SO2 in chamber process

Option C: Alkylation of hydrocarbons

Option D: None of these

Correct Answer: Alkylation of hydrocarbons ✔

Option A: Most suitable for a second order reaction

Option B: Most suitable for a reversible reaction

Option C: Completely self-supporting in its thermal energy requirements

Option D: Isothermal in nature

Correct Answer: Completely self-supporting in its thermal energy requirements ✔

Option A: Increasing the concentration of one of the reactants

Option B: Increasing the concentration of one or more of the products

Option C: Removal of at least one of the products at regular interval

Option D: None of these

Correct Answer: Increasing the concentration of one or more of the products ✔

Option A: -rA = (k . PA . PB)/(1 + KAPA + KPPP)

Option B: -rA = (k . PA

Option C: -rA = (k . PA . PB)/(1 + KAPB + KBPB . KPPP)

Option D: -rA = (k . PA . PB)/(1 + KAPA)

Correct Answer: -rA = (k . PA . PB)/(1 + KAPA + KPPP) ✔

Option A: K3 = K1.K2

Option B: K3 = (K1.K2)0.5

Option C: K3(K1+K2)/2

Option D: K3 = (K1.K2)2

Correct Answer: K3 = K1.K2 ✔

Option A: Batch reactor is preferred over a single CSTR for high yield

Option B: Tubular reactor is preferred over a single CSTR for high yield

Option C: Both A. and B.

Option D: Single CSTR is the most suitable

Correct Answer: C. Both A. and B. ✔

Option A: Large reactor followed by smaller one

Option B: Smaller reactor followed by larger one

Option C: Either of the arrangement A. or B. will give the same yield

Option D: Data insufficient, can’t be predicted

Correct Answer: C. Either of the arrangement A. or B. will give the same yield ✔

Option A: 256

Option B: 512

Option C: 112

Option D: 612

Correct Answer: 512 ✔

Option A: 0.15

Option B: 0.30

Option C: 0.60

Option D: 0.90

Correct Answer: 0.60 ✔

Option A: > 1

Option B: < 1

Option C: 1

Option D: 0

Correct Answer: 1 ✔

Option A: Catalytic

Option B: Autocatalytic

Option C: Photochemical

Option D: None of these

Correct Answer: Autocatalytic ✔

Option A: Time

Option B: Useful volume of the tank

Option C: Diameter of the reactor

Option D: None of these

Correct Answer: Time ✔

Option A: Is greater than

Option B: Is smaller than

Option C: Equals

Option D: Can be either greater or smaller than (depends on the type of reaction)

Correct Answer: Equals ✔

Option A: Feed rate

Option B: Reactor volume

Option C: Extent of reaction

Option D: All A., B. and C.

Correct Answer: D. All A., B. and C. ✔

Option A: There is no mixing in longitudinal direction

Option B: Mixing takes place in radial direction

Option C: There is a uniform velocity across the radius

Option D: All A., B. and C.

Correct Answer: D. All A., B. and C. ✔

Option A: Adiabatic

Option B: Isothermal

Option C: Non-adiabatic

Option D: None of these

Correct Answer: Non-adiabatic ✔

Option A: Increases

Option B: Decreases

Option C: Remain same

Option D: Becomes infinite

Correct Answer: Increases ✔

Option A: Stirred tank

Option B: Tubular flow

Option C: Batch

Option D: Fixed bed

Correct Answer: Stirred tank ✔

Option A: 8

Option B: 16

Option C: 1/8

Option D: 1/16

Correct Answer: 16 ✔

Option A: Pressure has no effect

Option B: Backward reaction is favoured

Option C: Forward reaction is favoured

Option D: None of these

Correct Answer: Pressure has no effect ✔

Option A: Pulse

Option B: Step

Option C: Both A. & B.

Option D: Neither A. nor B.

Correct Answer: C. Both A. & B. ✔

Option A: Reaction can be accomplished with small reactor

Option B: Conversion can be obtained with a high feed rate

Option C: Both A. and B.

Option D: None of these

Correct Answer: C. Both A. and B. ✔

Option A: 1.6

Option B: 2

Option C: 2.24

Option D: 2.5

Correct Answer: 2 ✔

Option A: DE = DM + DK

Option B: 1/DE = 1/DN + DK

Option C: DE = DM . DE

Option D: DE = DN/DE

Correct Answer: 1/DE = 1/DN + DK ✔

Option A: Surface chemical reaction

Option B: Adsorption

Option C: Desorption

Option D: None of these

Correct Answer: None of these ✔

Option A: Remain the same

Option B: Be halved

Option C: Also be doubled

Option D: Become one fourth

Correct Answer: Remain the same ✔

Option A: Have very high selectivity

Option B: Increase the activity of a catalyst

Option C: Provide large surface area with a small amount of active material

Option D: Inhibit catalyst poisoning

Correct Answer: Provide large surface area with a small amount of active material ✔