Free Chemical Reaction Engineering MCQs with Answers
395 Chemical Reaction Engineering MCQs from Chemical Engineering, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
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395 questions · page 8 of 20
- A. More than
- B. Less than
- C. Either B. or C.
- D. Equal to
Explanation: Chemical equilibrium is dynamic: forward and reverse reactions continue, but their rates are equal, giving no net change in composition.
Correct answer: Equal to- A. Has unit of time-1
- B. Is not a function of the unit of time
- C. Changes on changing the concentration units
- D. None of these
Explanation: For a first-order law, rate = kC, so k must have units of inverse time, such as s⁻¹.
Correct answer: Has unit of time-1- A. Twice
- B. Half
- C. Equal
- D. None of these
Explanation: When diffusion controls the observed rate, the measured activation energy is reduced because the rate is governed partly by transport…
Correct answer: Half- A. Removal of one of the products regularly
- B. Increase in the concentration of one of the reactants
- C. Increase in the concentration of one of the products
- D. None of these
Explanation: Adding a product shifts equilibrium toward the reactants to oppose the concentration increase, so the reverse reaction is favoured.
Correct answer: Increase in the concentration of one of the products145. With increase in temperature, the equilibrium _______________ rises in case of endothermic reaction?
- A. Constant
- B. Neither A. nor B.
- C. Both A. & B.
- D. Conversion
Explanation: Heating an endothermic system favours the forward reaction, increasing both the equilibrium constant and, under usual conditions, the…
Correct answer: Conversion- A. Microbial fermentation reaction
- B. Photochemical reactions
- C. Enzyme fermentation reaction
- D. Ammonia synthesis reaction
Explanation: Microbial fermentation is commonly treated as autocatalytic because the microorganisms or biomass formed during the reaction promote…
Correct answer: Microbial fermentation reaction- A. Increase
- B. Increase exponentially
- C. Decrease
- D. Remain unchanged
Explanation: For an irreversible reaction in a tubular flow reactor, conversion increases with residence or space time because reactant has more time…
Correct answer: Decrease- A. Only chemical
- B. Only physical
- C. Neither A. nor B.
- D. Both A. & B.
Explanation: A heterogeneous catalytic reactor requires physical steps such as diffusion and adsorption, as well as chemical surface reaction and…
Correct answer: Both A. & B.- A. Equal to
- B. Triple
- C. Double
- D. None of these
Explanation: Space time is reactor volume divided by inlet volumetric flow, while holding time uses the actual fluid volume flow inside the reactor.
Correct answer: Equal to- A. Of very large activation energy of many bodies
- B. Of low probability of many body collisions
- C. Many body collisions are not favoured energetically
- D. Of requirement of very large concentration for such reactions
Explanation: A high-molecularity reaction requires several particles to collide simultaneously with suitable energy and orientation.
Correct answer: Of low probability of many body collisions- A. Equilibrium constant
- B. Activation energy
- C. Final products
- D. Heat of reaction
Explanation: A catalyst provides an alternative reaction pathway with lower activation energy, increasing the reaction rate in both directions.
Correct answer: Activation energy- A. Lack of intraparticle diffusion resistance
- B. Presence of two mobile phases
- C. Both A. and B.
- D. Neither A. nor B.
Explanation: In a slurry reactor, finely divided catalyst particles are suspended in a liquid, usually with a gas phase also present, giving two mobile…
Correct answer: Both A. and B.- A. Maxima in the concentration of B
- B. AA. Maxima in the concentration of A
- C. Maxima in the concentration of C
- D. High exothermicity
Explanation: For the consecutive sequence A → B → C, the intermediate B is first formed and then consumed, so its concentration rises to a maximum and…
Correct answer: Maxima in the concentration of B- A. Consecutive or side
- B. All A., B. and C.
- C. Mixed
- D. Parallel or side
Explanation: Multiple reactions include consecutive or series reactions, parallel or side reactions, and combinations of these called mixed reactions.
Correct answer: All A., B. and C.- A. Is always equal to the overall order of reaction
- B. May not be equal to the order of reaction
- C. Both B. and C.
- D. Can't have a fractional value
Explanation: Molecularity applies to an elementary reaction and is the number of participating species, so it is a positive integer.
Correct answer: Both B. and C.- A. 0.80
- B. 1.33
- C. 1.60
- D. 2.67
Explanation: For a CSTR, the required residence time is τ = Cₚ₀X/(-rₚ). At 40% conversion, Cₚ = 0.6Cₚ₀ and Cᵣ = 0.4Cₚ₀, giving -rₚ = 0.25Cₚ₀ and τ =…
Correct answer: 1.60- A. A P.F. reactor in series
- B. More CSTR's in series
- C. A P.F. reactor in parallel
- D. More CSTR's in parallel
Explanation: Adding CSTRs in series makes the concentration profile approach that of a plug-flow reactor, generally increasing conversion for the same…
Correct answer: More CSTR's in series- A. k ∝ √T
- B. None of these
- C. k ∝ T e-E/RT
- D. k ∝ e-E/RT
Explanation: Arrhenius behavior is k = A exp(-E/RT), so the temperature-dependent part is proportional to exp(-E/RT).
Correct answer: k ∝ e-E/RT- A. nD = (n + 1)/2
- B. nD = n/2
- C. nD = n + 1
- D. None of these
Explanation: Under strong intraparticle diffusion control, the effectiveness factor introduces a concentration dependence that changes the observed…
Correct answer: nD = (n + 1)/2- A. A
- B. A + N
- C. N
- D. A - N
Explanation: Threshold energy is the energy level required to reach the activated state, measured from the zero-energy reference.
Correct answer: A + N