All Free Chemical Engineering MCQs with Answers
Every Chemical Engineering question in the bank, across all chapters, each with the correct answer and a written explanation. Free and unlimited, with no account needed.
6,983 questions · page 174 of 350
- 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- 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: Deposited3480. In a reversible reaction, a catalyst increases the rate of forward reaction__________________?
- 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