chemical engineering chemical reaction MCQs – Page 10

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 Review each marked answer and report any item that may be outdated or unclear.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

181. The reaction rate almost gets doubled for 10C rise in temperature. This is due to the fact that the_________________?
0

A. Value of threshold energy decreases

B. Fraction of molecules having threshold energy increases

C. Collision frequency increases

D. Increased temperature reduces the activation energy

182. Exposure of a photographic plate to produce a latent image is an example of _______________ reaction?
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A. Very slow

B. Very fast

C. Photochemical

D. Both B. and C.

183. In the fluid catalytic cracker (FCC), the cracking reaction is _____________ (i) and the regeneration is _______________ (ii) _______________?
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A. (i) endothermic (ii) endothermic

B. (i) exothermic (ii) exothermic

C. (i) exothermic (ii) endothermic

D. (i) endothermic (ii) exothermic

184. For a packed bed reactor; the presence of a long tail in the residence time distribution curve is an indication of ?
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A. Ideal plug flow

B. Channelling

C. Bypass

D. Dead zone

185. Organic catalysts differ from the inorganic catalyst in the sense that the former is________________?
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A. Active at very high temperature only

B. Active at cryogenic temperatures only

C. Prohibitively costly

D. Proteinous in nature

186. Helium-mercury method is used for the measurement of the ________________ of the catalyst?
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A. Surface area

B. Porosity

C. Pore volume

D. Both B. & C.

187. 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___________________?
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A. k2 CB0 > k1 CA0

B. CB0 > CA0

C. k CA0 > k2.CB0

D. CA0 > CB0

188. The heat of reaction__________________?
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A. Depends on the pressure only

B. Depends on the mechanism of reaction only

C. Depends on both pressure and mechanism of reaction

D. Is independent of the mechanism of reaction

189. ______________ catalytic reaction is involved in the thermal cracking of gas oil ?
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A. Homogeneous

B. Non-Homogeneous

C. Heterogeneous

D. Non-Heterogeneous

190. 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 ?
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A. 3-Jan

B. 3

C. 1/2

D. 9-Jan

191. A pollutant P degrades according to first order kinetics. An aqueous stream containing P at 2 kmole/m3 and volumetric flow rate 1m3 /h requires a mixed flow reactor of volume V to bring down the pollutant level to 0.5 kmole/m3. The inlet concentration of the pollutant is now doubled and the volumetric flow rate is tripled. If the pollutant level is to be brought down to the same level of 0.5 k.mole/m3, the volume of the mixed flow reactor should be increased by a factor of_______________?
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A. 3

B. 6

C. 3-Jul

D. 7

192. For series reaction, the relative yield__________________?
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A. Is always greater for plug-flow reactor than for the single CSTR of the same volume

B. Statement in A. is wrong

C. Decreases with increasing conversion

D. Both A. and C. hold good

193. 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?
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A. 2

B. 3

C. 1

D. 0

194. The size of plug flow reactor (PFR) for all positive reaction orders and for any given duty, is _____________________ that of mixed reactor?
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A. Unpredictable from the data

B. Smaller than

C. Equal to

D. Greater than

195. For a first order chemical reaction in a porous catalyst, the Thiele modulus is 10. The effectiveness factor is approximately equal to ____________________?
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A. 0.1

B. 0

C. 0.5

D. 1

196. Fractional conversion _________________ for an exothermic reversible chemical reaction, when the temperature is maximum?
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A. Remains unchanged

B. Decreases

C. Unpredictable from the data

D. Increases

197. Non-catalytic fluid-solid reactions are represented by _______________ model?
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A. Continuous reaction

B. Unreacted core

C. Both A. and B.

D. Neither A. and B.

198. A second order reaction of the form A + B ? C is called a pseudo-first order reaction, when____________________?
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A. CA0 > CB0

B. CB0 > CA0

C. CA0 = CB0

D. CB0 ? CB0

199. Effectiveness factor E. of a catalyst pellet is defined as, E = (actual rate within pore of the catalyst)/(rate if not snowed by pore diffusion), Effectiveness factor for a first order reaction is given by (where, T = Thiele modulus) ___________________?
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A. tan hT/tan T

B. tan hT/T

C. None of these

D. tan T/T

200. The sequence in which three CSTRs of volumes 5, 10 and 15 m3 will be connected in series to obtain the maximum production in a second order irreversible reaction is ____________________?
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A. 15, 10, 5

B. 5, 10, 15

C. 10, 5, 15

D. 10, 15, 5

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