chemical engineering chemical reaction Mcqs
251. Rate constant for a first order reaction does not depend upon reaction time, extent of reaction and the initial concentration of reactants; but it is a function of reaction temperature. In a chemical reaction, the time required to reduce the concentration of reactant from 100 gm moles/litre to 50 gm moles/litre is same as that required to reduce it from 2 gm moles/litre to 1 gm mole/litre in the same volume. Then the order of this reaction is ?
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A. 1

B. 2

C. 3

D. 0

252. The rate of reaction of a/an ______________ reaction is not affected by temperature rise ?
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A. Autocatalytic

B. Zero order

C. Consecutive

D. Photochemical
253. From collision theory, the reaction rate constant is proportional to_________________?
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A. Tm exp (-E/RT)

B. exp (-E/RT)

C. ?T

D. exp (-E/2RT)

254. Slurry reactors are characterised by the_________________?
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A. Lack of intraparticle diffusion resistance

B. Presence of two mobile phases

C. Both A. and B.

D. Neither A. nor B.

255. Pick out the wrong statement ?
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A. The residence time for all the elements of fluid in case of a P.F.R. need not be same

B. A flat velocity profile exists in a plug flow reactor

C. Chemical reactions with high activation energy are very temperature sensitive

D. n one

E. Half life of a reaction increases with increased initial concentration for reaction orders more

256. For nearly isothermal operation involving large reaction time in a liquid-phase reaction, the most suitable reactor is a _________________ reactor?
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A. Fixed bed

B. Stirred tank

C. Tubular flow

D. Batch

257. Enzymes (a protein) are catalysts found in organisms. Its efficiency of catalysing a reaction is due to its capacity to lower the activation energy of the reaction. The enzyme ptyalin used for food digestion is present in ___________________?
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A. Saliva

B. Blood

C. Gland

D. Intestine

258. ____________ is the controlling step in a highly temperature sensitive fluid-solid non-catalytic reaction ?
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A. Chemical reaction

B. None of these

C. Gas film diffusion

D. Ash diffusion

259. The most unsuitable reactor for carrying out reactions in which high reactant concentration favours high yields is________________________?
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A. Series of CSTR

B. Plug flow reactor

C. PFR in series

D. Backmix reactor
260. Half-life period for a first order reaction is _____________ the initial concentration of the reactant?
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A. Inversely proportional to

B. Independent of

C. Directly proportional to

D. None of these

261. Pick out the wrong statement ?
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A. In a batch reactor, which is exclusively used for liquid phase reactions; temperature pressure and composition may vary with time

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

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

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

262. When the density of the reaction mixture is constant in a chemical reaction, the ratio of the mean residence time to space time is__________________?
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A. 1

B. 0

C. > 1

D. < 1

263. The rate of forward reaction, at chemical equilibrium is ______________ the rate of backward reaction?
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A. More than

B. Equal to

C. Less than

D. Either B. or C.

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

B. 2/3 kW

C. 1 kW

D. 4 kW

265. When the reaction occurs in the diffusion controlled region, the apparent activation energy as measured is only _______________ the true value?
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A. Half

B. Equal

C. Twice

D. None of these

266. The effect of increasing pressure on the gaseous equilibrium of the reaction 2X + 3Y ? 3X + 2Y indicates that____________________?
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A. None of these

B. Forward reaction is favoured

C. Pressure has no effect

D. Backward reaction is favoured

267. In an ideal mixed reactor (at steady state), the ___________________?
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A. All A., B. and C.

B. Space time is equivalent to holding time for constant density systems

C. Composition throughout the reactor remains same

D. Exit stream has the same composition as the fluid within the reactor

268. Rate of a chemical reaction is not influenced by the__________________?
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A. Temperature

B. Number of molecules of reactants taking part in a reaction

C. Catalyst

D. Reactants concentration

269. For the chemical reaction P ? Q, it is found that the rate of reaction doubles as the concentration of P is doubled. If the reaction rate is proportional to Cp n, then what is the value of n for this chemical reaction ?
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A. 3

B. 0

C. 1

D. 2

270. What is the unit of the rate constant in a chemical reaction in which 10% of the reactant decomposes in one hour, 20% in two hours, 30% in three hours and so on ?
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A. Litre/mole

B. Litre/mole.second

C. Litre/second

D. Moles/litre.second

271. Which of the following factors control the design of a fluid-solid reactor ?
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A. Size distribution of solids being treated

B. Reaction kinetics for single particle

C. All A., B. and C.

D. Flow patterns of solids and fluid in the reactor

272. The importance of diffusion in a catalyst are increased by ____________________?
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A. Small pore diameter

B. All A., B. and C.

C. Large catalyst particle size

D. An active surface of the catalyst

273. Pick out the correct statement ?
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A. A chemical reaction accompanied by evolution of heat is called an endothermic reaction

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

C. A chemical reaction accompanied by absorption of heat is called an exothermic reaction

D. Chemical equilibrium state is dynamic in nature

274. Signal normally used to study non-ideal flow by stimulus response technique is _______________ input?
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A. Pulse

B. Step

C. Both A. & B.

D. Neither A. nor B.

275. A backmix reactor_________________?
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A. Is most suitable for gas phase reaction

B. Employs mixing in axial direction only

C. Is same as ideal stirred tank reactor

D. Is same as plug-flow reactor

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

B. 2.5

C. 95

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

B. 10C

C. 5C

D. 100C

278. 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?
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A. Third

B. Second

C. First

D. Any
279. In case of a _____________ reactor, the composition in the reactor and at the exit of the reactor is the same ?
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A. Tubular

B. Back-mix

C. Batch

D. Semi-batch

280. For multiple reactions, the flow pattern within the vessel affects the ____________________?
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A. Size requirement

B. Distribution of reaction products

C. Both A. and B.

D. Neither A. nor B.

281. The equilibrium constant for the reversible reaction as shown in the bellow figure, is affected by the__________________?
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A. Presence or absence of inerts

B. Temperature of the system

C. Pressure of the system

D. Kinetics of the reaction

282. The rate at which a chemical substance reacts is proportional to its _____________________?
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A. Equivalent weight

B. Molecular weight

C. Atomic weight

D. Active mass
283. Catalytic action in a catalytic chemical reaction follows from the ability of catalyst to change the ___________________?
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A. Activation energy

B. None of these

C. Equilibrium constant

D. Heat of reaction

284. Pick out the wrong statement?
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A. mentary

B. concentration of A decreases and the rate is proportional to the concentration of A

C. In a first order reaction, A ? products; the reaction becomes slower as it proceeds, because

D. Transition state theory approaches the problem of calculating reaction rates by concentrating

E. e of an eddy to the solute decreases</strong>

F. the idea of activated complexes

285. Which one is the rate controlling step in a solid-gas non-catalytic reaction occurring at very high temperature ?
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A. Pore diffusion

B. Film diffusion

C. Ash layer diffusion

D. Chemical reaction

286. Photochemical reaction rate does not depend significantly on temperature, because____________________?
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A. It is a reversible reaction

B. It is an exothermic reaction

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

D. None of these

287. ______________ explains the mechanism of catalysis?
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A. None of these

B. Collision theory

C. Thermodynamics

D. Activated complex theory
288. Pick out the wrong statement?
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A. Activation energy for a reaction is obtained from the intercept of the Arrhenius plot

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

C. Presence of inerts affects the equilibrium conversion of

D. Use of different catalysts in a reversible catalytic chemical reaction does not change the

E. ilibrium composition

289. 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________________?
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A. 1

B. 4

C. 3

D. 2
290. Pick out the wrong statement ?
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A. A batch reactor cannot be used to study the kinetics of catalytic reaction

B. For studying a chemical reaction, it is desirable to monitor the reactants during initial stages

C. Study of non-ideal flow reactor is done experimentally by stimulus-response technique

D. Hold back is defined as the fraction of material that stays longer than the mean residence time

E. the products during the final stages of reaction

291. For a mixed flow reactor operating at steady state, the rate of reaction is given by______________?
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A. (FA0/V) (dCA/dt)

B. #NAME?

C. (FA0/V) + (dCA/dt)

D. (FA0/V) XA
292. Consider the n th order irreversible liquid phase reaction A ? B. Which one of the following plots involving half life of the reaction (t1/2) and the initial reactant concentration (CA0) gives a straight line plot ?
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A. CA0 Vs ln t1/2

B. ln CA0 Vs t1/2

C. CA0 Vs t1/2

D. ln CA0 Vs ln t1/2

293. With increase in K2/K1 in case of a unimolecular type elementary reactions as shown in the bellow figure, the fractional yield of R in mixed reactor (for a given conversion of A) ?
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A. Increases

B. Increases linearly

C. Decreases

D. Remain same

294. Pick out the wrong statement ?
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A. For a second order reaction, the slope of the graph/plot between rate and (concentration) is

B. Visible radiation provides the necessary activation energy in photochemical reactions

C. Molecularity of the reaction is always a whole number greater than zero

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

E. al to the rate constant (k)

295. Holding time for flow reactors is _______________ the space time, for constant fluid density ?
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A. Triple

B. Equal to

C. None of these

D. Double

296. For a vapour phase catalytic reaction (A + B ? P) which follows the Ridel mechanism and the reaction step is rate controlling, the rate of reaction is given by (reaction rate is irreversible, product also absorbs) ?
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A. -rA = (k . PA . PB)/(1 + KAPA + KPPP)

B. #8211; k1PP)/(1 + KAPA + KPPP)

C. -rA = (k . PA . PB)/(1 + KAPA)

D. -rA = (k . PA . PB)/(1 + KAPB + KBPB . KPPP)

E. -rA = (k . PA

297. Sum of the powers of the concentration terms in the rate equation is called the _____________ of the reaction?
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A. Order

B. Overall order

C. None of these

D. Molecularity

298. The energy balance equation over a tubular reactor under transient conditions is________________?
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A. A linear partial differential equation

B. An algebraic differential equation

C. A non-linear partial differential equation

D. An ordinary non-linear differential equation

299. The excess energy of reactants in a chemical reaction required to dissociate into products is termed as the _______________ energy?
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A. Threshold

B. Activation

C. Binding

D. Potential

300. 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)?
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A. Remain same

B. Increases linearly

C. Decreases

D. Increases