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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- A. Has altogether three streams either entering or leaving
- B. Processes three reactants at different flow rates
- C. Employs all the three phases (i.e. solid, liquid and gas)
- D. Processes three reactants with same flow rate
Explanation: A trickle-bed reactor contains a fixed solid catalyst while gas and liquid flow through the bed, so all three phases are present.
Correct answer: Employs all the three phases (i.e. solid, liquid and gas)- A. Autocatalytic
- B. Zero order
- C. Consecutive
- D. Photochemical
Explanation: Photochemical reactions are initiated by absorbed light, so their rate is governed mainly by radiation intensity and quantum efficiency…
Correct answer: Photochemical- A. CSTR followed by a plug flow reactor
- B. CSTR in series
- C. A plug flow reactor followed by CSTR
- D. A CSTR
Explanation: A CSTR provides good mixing and temperature control, which is valuable for an exothermic reaction, while the following PFR provides…
Correct answer: CSTR followed by a plug flow reactor- A. A well stirred batch reactor
- B. A plug-flow reactor
- C. A single CSTR
- D. CSTR's connected in series
Explanation: A single CSTR is perfectly mixed, so material leaving it has the same composition as material throughout the vessel and experiences…
Correct answer: A single CSTR- A. Constant throughout the reactor
- B. Maximum at the exit of the reactor
- C. Maximum at the centre of the reactor
- D. Maximum at the inlet of the reactor
Explanation: For an endothermic adiabatic reactor, the temperature falls as the reaction proceeds, while reactant concentration also decreases.
Correct answer: Maximum at the inlet of the reactor- A. At low P and low T
- B. At low P and high T
- C. At high P and high T
- D. At high P and low T
Explanation: The forward reaction is exothermic, so low temperature shifts equilibrium toward B.
Correct answer: At low P and low T- A. Activation
- B. Thermal
- C. Threshold
- D. Binding
Explanation: Activation energy is the excess energy reactant molecules must acquire to reach the activated complex and react.
Correct answer: Activation- A. Zero
- B. Second
- C. First
- D. None of these
Explanation: For a second-order reaction, the half-life is t₁/₂ = 1/(kC₀), so both the initial concentration and rate constant are needed.
Correct answer: Second- A. Goes through a minimum along the length of the reactor
- B. Goes through a maximum along the length of the reactor
- C. Is maximum at the inlet of the reactor
- D. Is maximum at the exit of the reactor
Explanation: In an endothermic adiabatic PFR, temperature decreases along the reactor, lowering the rate constant, and reactant concentration also…
Correct answer: Is maximum at the inlet of the reactor- A. Decay reactions
- B. Pore diffusion
- C. Form of surface attack by poison
- D. All A., B. and C.
Explanation: Pellet deactivation depends on the decay mechanism, resistance to pore diffusion, and how the poison attacks or deposits on the active…
Correct answer: All A., B. and C.- A. Deposited
- B. Chemisorbed
- C. Selectivity
- D. Stability
Explanation: Carbon formed during gas-oil cracking remains deposited on the catalyst surface or inside its pores, so it is classified as a deposited…
Correct answer: Deposited- A. Only
- B. And the backward reaction equally
- C. And decreases that of the backward reaction
- D. To a greater extent than that of the backward reaction
Explanation: A catalyst provides an alternative pathway with lower activation energy for both directions of a reversible reaction.
Correct answer: And the backward reaction equally- A. Space time is equivalent to holding time for constant density systems
- B. Composition throughout the reactor remains same
- C. All A., B. and C.
- D. Exit stream has the same composition as the fluid within the reactor
Explanation: In an ideal mixed reactor, perfect mixing makes the composition uniform and equal to the exit composition.
Correct answer: All A., B. and C.- A. Large catalyst particle size
- B. An active surface of the catalyst
- C. Small pore diameter
- D. All A., B. and C.
Explanation: Diffusion becomes more important when particles are larger, pores are narrower, or the catalyst is more active and consumes reactant…
Correct answer: All A., B. and C.- A. 3
- B. 1
- C. 1/3
- D. 32
Explanation: Space time is reactor volume divided by the inlet volumetric flow rate: τ = V/v₀ = 3 L/(1 L s⁻¹) = 3 s. The correct option is therefore b.
Correct answer: 3- A. Increases
- B. Remain constant
- C. Decreases
- D. Unpredictable
Explanation: For a first-order batch reaction, the integrated relation is −ln(1 − X) = kt, so conversion at a fixed time depends on k and t, not on the…
Correct answer: Remain constant- A. 2 & 2
- B. 11 & 2
- C. 2 & 1
- D. 1 & 1
Explanation: Methyl acetate hydrolysis is bimolecular because ester and water participate in the overall reaction, giving molecularity 2.
Correct answer: 2 & 1- A. K α e-E/RT
- B. K α eE/RT
- C. K α T . e-E/RT
- D. K α √T . e-E/RT
Explanation: Arrhenius behaviour is k = A exp(-E/RT), so the rate constant increases with temperature because the negative exponent becomes less…
Correct answer: K α e-E/RT- A. Directly proportional to
- B. Independent of
- C. Inversely proportional to
- D. None of these
Explanation: For a first-order reaction, t₁/₂ = 0.693/k, which contains no initial concentration term.
Correct answer: Independent of- A. Decrease
- B. Increase
- C. No change
- D. Either A. or B., depends on the type of reaction
Explanation: For an ideal CSTR, the recycle stream has the same composition as the reactor outlet, so its effects cancel in the overall material…
Correct answer: No change