chemical engineering chemical reaction MCQs – Page 13

Practise multiple-choice questions from chemical engineering chemical reaction for competitive examinations and subject revision. Review each marked answer and report any item that may be outdated or unclear.

chemical engineering chemical reaction Mcqs

241. If the rate of a chemical reaction becomes slower at a given temperature, then the__________________?
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A. Initial concentration of the reactants remains constant

B. Free energy of activation is higher

C. Entropy changes

D. Free energy of activation is lower

242. The rate constant of a reaction is a function of the ___________________?
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A. Extent of reaction

B. Initial concentration of the reactants

C. Temperature of the system

D. Time of reaction

243. The dispersion number of perfect mixed flow is__________________?
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A. > 150

B. 0

C. ?

D. < 2100

244. A catalyst promoter_________________?
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A. Acts as a catalyst support

B. Itself has very high activity

C. Improves the activity of a catalyst

D. All A., B. and C.

245. Molecularity of an elementary reaction, P + Q ? R + S is ____________________?
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A. 2

B. 1

C. 3

D. 4

246. The fractional volume change between no conversion and complete conversion, for the isothermal gas phase reaction, 2A ? R, is___________________?
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A. -0.5

B. 0.5

C. 1

D. 1.5

247. Rate of a chemical reaction is not affected by the____________________?
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A. Temperature

B. Catalyst

C. Number of molecules of reactants taking part in the reaction

D. Reactants concentration

248. Fluid flow in a real packed bed can be approximated as ________________ model?
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A. Plug flow

B. Mixed flow

C. Dispersion

D. Tank in series

249. A typical example of an exothermic reversible reaction conducted at high pressure in industry is____________________?
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A. Methanol synthesis

B. Dehydration of ethanol

C. Reformation of methane

D. Polymerisation of ethylene

250. Which of the following is a controlling factor in very fast heterogeneous reaction ?
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A. Pressure

B. Composition of reactant

C. Temperature

D. Heat and mass transfer effects

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

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