chemical engineering chemical reaction Mcqs
151. The rate of reaction does not decrease appreciably as the reaction proceeds in case of ______________ reactions?
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A. Autothermal

B. Endothermic

C. Exothermic

D. Autocatalytic
152. Oil is hydrogenated using nickel catalyst in a __________________ reactor?
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A. Fluidised bed

B. Slurry

C. Batch

D. Fixed bed

153. Pure A in gas phase enters a reactor 50% of this A is converted to B through the reaction, A ? 3B. Mole fraction of A in the exit stream is______________________?
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A. 2-Jan

B. 5-Jan

C. 1/3

D. 4-Jan

154. Fractional conversion _____________ with increase in pressure for ammonia synthesis reaction i.e., N2 + 3H2 ? 2NH3?
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A. Decreases

B. Unpredictable from the data

C. Remains unchanged

D. Increases
155. Photo-chemical reactions occur in presence of ___________________?
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A. Sunlight

B. Solid catalysts

C. Darkness

D. Monochromatic radiation only

156. A first order reaction is to be treated in a series of two mixed reactors. The total volume of the two reactors is minimum, when the reactors are_____________________?
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A. None of these

B. Equal in size

C. Of such size that the ratio of their volumes is < 5

D. Of different sizes

157. What is the order of chemical reaction as shown in the bellow figure, if it is found that the reaction rate doubles on doubling the concentration of B and also the reaction rate doubles when the concentrations of both A & B were doubled and quadrupled when the concentrations of both B & C were doubled ?
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A. 2

B. 1

C. 4

D. 3

158. The rate constant of a chemical reaction increases by increasing the______________________?
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A. Temperature

B. Pressure

C. Reactants concentration

D. None of these

159. The conversion of a reactant, undergoing a first order reaction, at a time equal to three times the half life of the reaction is ?
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A. 0.425

B. 0.875

C. Data insufficient to calculate

D. 0.5

160. Rate of an autocatalytic chemical reaction is a function of ___________________?
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A. Temperature only

B. All A., B. and C.

C. Pressure only

D. Composition only

161. For the gaseous reaction 2A ? B, where the feed consists of 50 mole % A and 50 mole % inerts, the expansion factor is___________________?
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A. -0.25

B. -0.5

C. 1

D. 0

162. A catalyst in a chemical reaction____________________?
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A. All A., B. and C.

B. Decreases the activation energy

C. Alters the reaction mechanism

D. Increases the frequency of collisions of reacting species

163. The optimum performance for reactors operating in parallel is obtained when the feed stream is distributed in such a way, that the_________________?
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A. Larger reactors have more space time compared to smaller ones

B. None of these

C. Space time for each parallel line is same

D. Space time for parallel lines is different

164. Mean residence time is equal to the space time, when_________________?
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A. The temperature, pressure and the density of reaction mixture remains constant throughout the

B. The feed rate is measured at temperature and pressure in the reactor

C. ctor

D. All A., B. and C.

E. There is no change in number of moles in gaseous reaction

165. Which of the following is not a unit of reaction rate ?
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A. Moles formed/volume of reactor) (time)

B. Moles for med/(surface of catalyst) (time)

C. None of these

D. Mole formed/volume of catalyst) (time)

166. Collision theory gives the rate constant for bimolecular reaction as___________________?
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A. None of these

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

C. K ? eE/RT

D. K ? e-E/RT
167. Which of the following fixes the volume of a batch reactor for a particular conversion and production rate ?
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A. Operating conditions (e.g. pressure and temperature)

B. Density of mixture

C. None of these

D. Rate constant

168. A plug-flow reactor is characterized by _____________________?
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A. Presence of axial mixing

B. Presence of lateral mixing

C. High capacity

D. Constant composition and temperature of reaction mixture

169. Which of the following is not a theory of homogeneous reaction ?
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A. Collision theory and activated complex theory

B. Chain reaction theory

C. Radiation hypothesis

D. None of these
170. Decomposition rate of a liquid X which decomposes as per the reaction as shown in the bellow figure is given by________________?
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A. (K1 + K2 + K3) CX

B. (K1 + K2) CX

C. K1 . CX

D. (K2 + K3) CX

171. A first order reaction A ? B occurs in an isothermal porous catalyst pellet of spherical shape. If the concentration of A at the centre of the pellet is much less than at the external surface, the process is limited by__________________?
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A. External mass transfer

B. Diffusion within the pellet

C. Reaction

D. None of the above

172. The enzyme which can catalyse the conversion of glucose to ethyl alcohol is ___________________?
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A. Maltase

B. Diastase

C. Invertase

D. Zymase
173. A batch reactor suffers from following disadvantage ?
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A. All A., B. and C.

B. Poor product quality control

C. High labour and handling cost

D. High shutdown time requirement for emptying, cleaning and refilling

174. The rate expression for a heterogeneous catalytic reaction is given by, rA = K.KA PA(1 + KA.PA + KR.PR), where K is surface reaction rate constant and KA and KR are absorption equilibrium constants of A and R respectively. If KR PR >> (1 + KA PA), the apparent activation energy EA is equal to (given E is the activation energy for the reaction and ?HR and ?HA are the activation energies of adsorption of R and A) ?
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A. E + ?HA

B. E

C. ?HA + ?HR

D. E + ?HA ?HR)
175. Most important characteristics of gas-liquid reactors are the________________?
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A. Specific inter-facial area

B. Liquid hold-up

C. Both A. and B.

D. None of these

176. The order of the chemical reaction as shown in the bellow figure, whose rate equation is given as -rA = KCA_________________?
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A. 0

B. 2

C. 1

D. 3

E. CB is

177. Kinetics of a catalytic reaction can be best studied on a/an ______________ reactor?
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A. Integral (plug flow)

B. Mixed

C. Differential (flow)

D. Either A., B. and C.
178. In an exothermic reaction, the energy of the reacting substances as compared to that of products is____________________?
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A. Either A. or B., depends on order of reaction

B. More

C. Less

D. Same

179. The minimum energy required to allow a chemical reaction to proceed is termed as the threshold energy . Chemical reactions with low activation energy are ________________?
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A. Insensitive to temperature changes

B. Highly temperature sensitive

C. Always irreversible

D. Mostly irreversible

180. If pore diffusion is the controlling step in a solid catalysed reaction, the catalyst___________________?
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A. Porosity is of less importance

B. Internal surface area is utilised efficiently

C. None of these

D. Porosity is very important

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