chemical engineering chemical reaction Mcqs
301. Transition state theory gives the rate constant as__________________?
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A. K ? T . e-E/RT

B. K ? eE/RT

C. K ? e-E/RT

D. K ? ?T . e-E/RT

302. consecutive reaction, as shown in the bellow figure, is characterised by __________________?
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A. High exothermicity

B. Maxima in the concentration of A

C. Maxima in the concentration of C

D. Maxima in the concentration of B
303. Pick out the correct statement?
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A. Pore volume and porosity of a catalyst is measured by Brunauer-Emmett-Teller (BET)

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

C. hnique

D. A lower temperature favours the reaction of lower activation energy

E. The rate controlling step in a reaction involving many steps is the fastest step

304. The catalyst in a second order reversible reaction increases the rate of the forward reaction___________________?
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A. And decreases that of backward reaction

B. And backward reaction equally

C. Only

D. To a greater extent than that of the backward reaction

305. A catalyst loses its activity due to__________________?
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A. Loss in surface area of the active component

B. Covering of the catalytic active sites by a foreign substance

C. All A., B. and C.

D. Agglomeration of metal particles caused by thermal sintering of the solid surface

306. For a reaction of the type of bellow given figure, the rate of reaction (- rx) is given by___________________?
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A. (K1 + K2+K3) CX

B. K1CV K2CX

C. (K1 + K1) CX

D. (K1 K2) CX

307. A back mix reactor is___________________?
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A. Suitable for gas phase reactions

B. Same as ideal stirred tank reactor

C. Same as plug flow reactor (PFR)

D. Ideal at very low conversion

308. The units of frequency factor in Arrhenius equation_________________?
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A. Depend on temperature, pressure etc. of the reaction

B. Depend on the order of the reaction

C. Are the same as those of the rate constant

D. Are cycles per unit time

309. The rate controlling step for the heterogeneous irreversible catalytic reaction A(g) + B(g) ? C(g) is the surface reaction of absorbed A with absorbed B to give adsorbed C. The rate expression for this reaction can then be written as (where, KA, KB and KC are the equilibrium constants and is the rate constant of the rate controlling step) ?
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A. k KAKB pApB / (1 + KApA + KBpB + KCpC)

B. k KAKB pApB / (1 + KApA + KBpB)

C. k KA pApB / (1 + KApA + KBpB)

D. k KAKB pApB / (1 + KApA + KBpB + KCpC)2
310. BET apparatus_______________________?
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A. Is made entirely of stainless steel

B. None of these

C. Measures the catalyst surface area directly

D. Operates at very high pressure

311. Considering the endothermic dissociation of CaCO3 in a closed vessel (CaCO3 ? CaO + CO2), the pressure of CO2 increases, if____________________?
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A. The temperature is increased

B. None of these

C. A catalyst is added

D. An inert gas is pumped keeping the temperature constant

312. In a reversible reaction, a catalyst increases the rate of forward reaction__________________?
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A. To a greater extent than that of the backward reaction

B. Only

C. And decreases that of the backward reaction

D. And the backward reaction equally
313. Specific rate constant for a second order reaction__________________?
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A. Is independent of temperature

B. Varies with temperature

C. Depends on the nature of the reactants

D. Both B. and C.
314. In flow reactors, the performance equations interrelate the rate of reaction to the___________________?
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A. All A., B. and C.

B. Extent of reaction

C. Reactor volume

D. Feed rate

315. Second order consecutive irreversible reaction as shown in the bellow figure, were carried out in a constant volume isothermal batch reactor with different initial feed compositions. Reactor temperature was same in all the cases. In experiments where the ratio of concentration of B to that of A in the initial feed was less than 0.5, the concentration of B increased first, reached a maximum and then declined with time. However, for all experiments where this concentration ratio was 0.5 or above, concentration of B decreased monotonically with time right from the beginning. What is the ratio of the two rate constants (k1/k2) ?
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A. 2-Jan

B. 2

C. 4

D. 1/4
316. Chemical reaction rate of a component depends upon the______________________?
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A. All A., B. and C.

B. Temperature of the system

C. Composition of the component only

D. Pressure of the system

317. With increase in initial concentration, the fractional conversion of a first order reaction in a given time___________________?
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A. Increases

B. Remain constant

C. Decreases

D. Unpredictable

318. Exothermic reactions are best carried out in ________________?
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A. A CSTR

B. A plug flow reactor followed by CSTR

C. CSTR followed by a plug flow reactor

D. CSTR in series

319. In a/an ______________ reactor, there is exchange of heat with the surroundings with sizeable temperature variation?
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A. None of these

B. Adiabatic

C. Isothermal

D. Non-adiabatic
320. If in the gaseous phase reaction, N2O4 ? 2NO2, x is the part of N2O4 which dissociates, then the number of molecules at equilibrium will be___________________?
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A. (1 + x)

B. (1 x)2

C. (1 x)

D. (1 + x)2

321. For a solid catalysed chemical reaction, the effectiveness of solid catalyst depends upon the ______________ adsorption?
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A. Physical

B. Chemical

C. Both A. and B.

D. Neither A. nor B.

322. In a reaction, the threshold energy is equal to (where, A = activation energy N = normal energy of reactants) ?
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A. A N

B. N

C. A + N

D. A

323. A high space velocity means that a given__________________?
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A. Reaction can be accomplished with small reactor

B. Conversion can be obtained with a high feed rate

C. Both A. and B.

D. None of these

324. For a first order reaction carried out in a plug flow reactor, the space time is__________________?
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A. (1/k) ln C0/C

B. (1/k) ln C/C0

C. k ln C/C0

D. k ln C0/C

325. Reverse reaction in a chemical equilibrium is favoured by the________________?
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A. Increase in the concentration of one of the reactants

B. None of these

C. Removal of one of the products regularly

D. Increase in the concentration of one of the products
326. Sometimes, batch process is preferred over continuous process, when the product___________________?
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A. Quality & yield cannot be achieved in continuous processes, because of long residence time

B. Sales demand is fluctuating

C. Both A. & B.

D. Neither A. nor B.

327. Reaction of benzene with chlorine gas to produce tri-chlorobenzene exemplifies a/an ______________ reaction?
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A. Consecutive

B. Elementary

C. Parallel

D. None of these

328. Pick out the wrong statement?
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A. Non-ideal flow takes place in reactors due to recycling, channeling or by creation of stagnant

B. The intercept of the Arrhenius plot is called the activation energy

C. A very high value of equilibrium constant, K (K >> 1) indicates that the reaction is practically

D. A particular chemical reaction is more temperature sensitive at low temperatures

E. eversible in nature

F. ions

329. For an autocatalytic reactor, the suitable reactor set up is__________________?
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A. P.F. reactors in series

B. CSTR in series

C. P.F. reactor followed by CSTR

D. CSTR followed by P.F. reactor
330. A spherical porous catalyst particle of radius R is subjected to reactant A which reacts to form B by a zero order surface reaction A ? B. Film mass transfer resistance is negligible and pore diffusion of A is rate controlling. The effectiveness factor of the catalyst is reported as 7/8. Which of the following statement is true?
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A. Inner catalyst core of radius R/2 does not participate in reaction

B. Effectiveness factor for a zero order reaction cannot be 7/8 as it must always be 1

C. Inner catalyst core of radius R/8 does not participate in reaction

D. Inner catalyst core of radius 7R/8 does not participate in reaction

331. For an ideal plug flow reactor, the value of Peclet number is_______________?
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A. 10

B. 0

C. ?

D. 1

332. Reactions with high activation energy are_____________________?
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A. Very temperature sensitive

B. Always reversible

C. Always irreversible

D. Temperature insensitive

333. Backmixing is most predominant in___________________?
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A. CSTRs connected in series

B. A single CSTR

C. A well stirred batch reactor

D. A plug-flow reactor

334. Effective diffusivity (DE) in a catalyst pellet is related to molecular diffusivity (DN) and Knudsen diffusivity (DK) as_________________?
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A. DE = DM + DK

B. 1/DE = 1/DN + DK

C. DE = DN/DE

D. DE = DM . DE

335. Pick out the wrong statement ?
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A. Molecularity of a reaction cannot be zero but the order of a reaction can be zero

B. In a multistep reaction, the slowest step is the rate determining step

C. Slow chemical reactions have generally high values of activation energy

D. In general, the rate of a reaction becomes triple for every 10C rise in temperature
336. Catalyst carriers___________________?
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A. Provide large surface area with a small amount of active material

B. Have very high selectivity

C. Increase the activity of a catalyst

D. Inhibit catalyst poisoning

337. The irreversible reaction is a special case of reversible reaction, if the________________?
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A. Conversion of the reactant at equilibrium condition is zero

B. Reactant concentration at equilibrium condition is zero

C. All A., B. and C.

D. Equilibrium constant is 1

338. The knowledge of initial concentration and rate constant is necessary to determine the half life time of a reaction of _______________ order?
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A. First

B. Zero

C. Second

D. None of these

339. In an exothermic chemical reaction, the reactants compared to the products have__________________?
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A. Higher temperature

B. More energy

C. Less energy

D. Same energy

340. When all the limiting reactant is consumed in the reaction, the operational yield _______________ the relative yield?
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A. Equals

B. Can be either greater or smaller than (depends on the type of reaction)

C. Is smaller than

D. Is greater than

341. An exothermic reaction takes place in an adiabatic reactor. The product temperature ______________ reactor feed temperature?
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A. May be greater or less than

B. Is always less than

C. Is always equal to

D. Is always greater than
342. A catalyst in a chemical reaction _______________ free energy change in the reaction?
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A. Decreases

B. Either A. or B.; depends on the type of catalyst

C. Increases

D. Neither A. nor B.

343. For a heterogeneous catalytic reaction____________________?
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A. The catalyst does not form an intermediate complex with the reactant

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

C. Free energy of activation is lowered in the presence of catalyst, which remains unchanged at

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

E. ch does not mean that catalyst concentration is important

F. end of reaction</strong>

344. Pick out the correct statement?
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A. Reactions with high activation energies are very temperature sensitive

B. Chemical equilibrium is a static state

C. A photochemical reaction is catalysed by light

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

345. In a reversible chemical reaction having two reactants in equilibrium, if the concentration of the reactants are doubled, then the equilibrium constant will________________?
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A. Become one fourth

B. Remain the same

C. Also be doubled

D. Be halved

346. For a zero order chemical reaction, the__________________?
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A. Products concentration increases linearly with time

B. All A., B. and C.

C. Plot of products concentration with time is a straight line through the origin

D. Half life period is directly proportion to the initial concentration of the reactants

347. If Thiele modulus is ________________, then the pore diffusion resistance in a catalyst may be considered as negligible?
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A. ?

B. < 0.5

C. > 0.5

D. 0

348. A batch reactor is suitable for__________________?
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A. Achieving cent percent conversion of reactants into products

B. Liquid phase reactions

C. Large scale gaseous phase reactions

D. Obtaining uniform polymerisation products in highly exothermic reactions

349. The rate of a chemical reaction is almost doubled for every 10C rise in temperature. The rate will increase ______________ times, if the temperature rises from 10 to 100C?
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A. 512

B. 112

C. 612

D. 256

350. Design of heterogamous catalytic reactor involves consideration of _______________ steps?
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A. Only chemical

B. Only physical

C. Both A. & B.

D. Neither A. nor B.