Multiple Choice Questions and Answers (MCQ) on Chemical Reaction Engineering
01. In case of staged packed bed reactors carrying out exothermic reaction, use
(A) High recycle for pure gas
(B) Plug flow for dilute liquid requiring no large preheating of feed
(C) Cold shot operations for a dilute solution requiring large preheating to bring the stream upto the reaction temperature
(D) All (A), (B) and (C)
Answer: Option D
02. The performance equations for constant density systems are identical for
(A) P.F.R. and backmix reactor
(B) P.F.R. and batch reactor
(C) P.F.R, batch reactor and backmix reactor
(D) Batch reactor and backmix reactor
Answer: Option B
03. The equilibrium constant of chemical reaction __________ in the presence of catalyst.
(A) Increases
(B) Decreases
(C) Remain unaffected
(D) Can either increase or decrease (depends on the type of catalyst)
Answer: Option C
04. Study of chemical kinetics is the easiest in the case of __________ reactions.
(A) Irreversible
(B) Reversible
(C) Surface
(D) Side
Answer: Option A
05. With increase in temperature, the equilibrium conversion of a reversible exothermic reaction
(A) Decreases
(B) Increases
(C) Remain unaffected
(D) Decreases linearly with temperature
Answer: Option A
06. The point selectivity of the product ‘Y’ in the reaction as shown in the bellow figure, is equal to
(A) K1/K2
(B) K2/K1
(C) K1 – K2
(D) K2 – K1
Answer: Option A
07. For reaction, P + 2 → 3R, molar rate of consumption of P is
(A) Double of that of Q
(B) Same as that of Q
(C) Half of that of Q
(D) 2/3rd of that of Q
Answer: Option C
08. Pick out the wrong statement.
(A) Visible radiation provides the necessary activation energy in photochemical reactions
(B) The order and molecularity of a complex reaction may not be the same
(C) For a second order reaction, the slope of the graph/plot between rate and (concentration) is equal to the rate constant (k)
(D) Molecularity of the reaction is always a whole number greater than zero
Answer: Option B
09. In a first order reaction, the time required to reduce the concentration of reactant from 1 mole/litre to 0.5 mole/litre will be __________ that required to reduce it from 10 moles/litre to 5 moles/litre in the same volume.
(A) More than
(B) Less than
(C) Same as
(D) Data insufficient; can’t be predicted
Answer: Option C
10. An irreversible first order reaction is being carried out in a CSTR and PFR of same volume. The liquid flow rates are same. The relative conversion will
(A) Be more in CSTR than in PFR
(B) Be more in PFR than in CSTR
(C) Be same in both cases
(D) Depend on the temperature
Answer: Option B
11. 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
(A) k2 CB0 > k1 CA0
(B) k CA0 > k2.CB0
(C) CB0 > CA0
(D) CA0 > CB0
Answer: Option A
12. Three plug flow reactors (PFR’s) of 4, 5 & 6 m3 volumes are arranged in two branches as shown below in the figure. If the total feed rate is 300 tons/hr, then for the same conversion in each branch, the feed rate through branch II should be __________ tons/hr.
(A) 100
(B) 150
(C) 200
(D) 225
Answer: Option A
13. Participation of __________ is involved in the occurrence of a chemical reaction.
(A) Protons
(B) Neutrons
(C) Electrons
(D) None of these
Answer: Option C
14. The first order gas phase reaction as shown in the bellow figure is conducted isothermally in batch mode. The rate of change of conversion with time is given by
(A) dXA/dt = k1 (1 – XA)2 (1 + 2XA)
(B) dXA/dt = k1 (1 – XA) (1 + 0.5XA)
(C) dXA/dt = k1 (1 – XA)
(D) dXA/dt = k1 (1 – XA)/(1 + XA)
Answer: Option C
15. A photochemical reaction is __________ light.
(A) Initiated by
(B) Accompanied with emission of
(C) Catalysed by
(D) Used to convert heat energy into
Answer: Option A
16. Coming soon.
17. Fluid flow in a real packed bed can be approximated as __________ model.
(A) Plug flow
(B) Dispersion
(C) Mixed flow
(D) Tank in series
Answer: Option B
18. The value of ‘n’ for a chemical reaction A → B, whose reaction rate is → CAn, will be __________ if the rate of the reaction increases by a factor of 8, when the concentration of is doubled.
(A) 0
(B) 1
(C) 2
(D) 3
Answer: Option D
19. The rate of an autocatalytic reaction as shown in the bellow figure, is given by -rA = k . CA . CB. In this case, the
(A) Plot of – rA Vs CA is a straight line with slope k
(B) Plot of – rA Vs CA is a hyperbola
(C) Rate of disappearance of reactant A is maximum, where CA = CB
(D) Both ‘b’ & ‘c’
Answer: Option D
20. __________ resistance is not involved in the combustion of a carbon particle.
(A) Gas film
(B) Ash
(C) Chemical reaction
(D) None of these
Answer: Option B
21. A stirred tank reactor compared to tubular-flow reactor provides
(A) More uniform operating conditions
(B) Permits operation at the optimum temperature for a long reaction time
(C) Higher overall selectivity for a first order consecutive reaction
(D) All (A), (B) and (C)
Answer: Option D
22. 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
(A) Equal in size
(B) Of different sizes
(C) Of such size that the ratio of their volumes is < 5
(D) None of these
Answer: Option A
23. Half life period of a first order irreversible reaction A → B is
(A) k/2
(B) ln k/2
(C) ln 2/k
(D) ln 0.5/k
Answer: Option C
24. An example of autothermal reactor operation is
(A) Sulphur dioxide oxidation
(B) Ethylene oxidation
(C) Benzene oxidation
(D) Ammonia synthesis
Answer: Option B
25. The value of Steric factor ‘P’ in the equation k = PZeE/RT usually ranges from
(A) 1.0 to 10-8
(B) 1.1 to 102
(C) 0.1 to 0.9
(D) None of these
Answer: Option A