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 184 of 350
- A. Continuous reaction
- B. Unreacted core
- C. Both A. and B.
- D. Neither A. and B.
Explanation: Fluid-solid non-catalytic reactions are commonly analysed using both the progressive or continuous-reaction model and the unreacted-core…
Correct answer: Both A. and B.- A. Density variation during reaction affects design
- B. Ratio of the volume of the mixed reactor to that of the plug-flow reactor decreases with order
- C. Reactor size is independent of the type of flow
- D. Mixed reactor is always larger than the plug-flow reactor
Explanation: For a positive reaction order, the rate generally decreases as reactants are consumed, so a CSTR operates everywhere at the low exit…
Correct answer: Mixed reactor is always larger than the plug-flow reactor- A. 1/2
- B. 1/3
- C. 1/9
- D. 3
Explanation: Since r is proportional to C_A^n, tripling the rate gives 3 = 9^n. Because 9^(1/2) = 3, the reaction order is n = 1/2.
Correct answer: 1/2- A. e-t/η
- B. e-t/η/η
- C. 1 - e-t/η
- D. 1 - (e-t/η/η)
Explanation: An ideal CSTR has an exponential residence-time distribution, E(t) = (1/η) exp(-t/η), where η is the mean residence time.
Correct answer: e-t/η/η- A. Rate constant
- B. Reaction speed
- C. Conversion
- D. Equilibrium constant
Explanation: The limiting reactant is consumed first according to stoichiometry, so it sets the maximum attainable conversion or theoretical yield.
Correct answer: Conversion- A. Operating conditions (e.g. pressure and temperature)
- B. Rate constant
- C. None of these
- D. Density of mixture
Explanation: For a specified conversion and production rate, the required material amount must be converted into reactor volume using the mixture…
Correct answer: Density of mixture- A. E
- B. E + ΔHA
- C. ΔHA + ΔHR
- D. E + ΔHA - ΔHR)
Explanation: When the denominator is dominated by K_RP_R, the rate is proportional to K K_A/K_R.
Correct answer: E + ΔHA - ΔHR)- A. 190
- B. 290
- C. 390
- D. 490
Explanation: Complete reaction would release 4 kmol/m³ × 50 kJ/mol = 200,000 kJ/m³, producing a temperature rise of 200,000/(1000 × 2) = 100 K.
Correct answer: 290- A. CA
- B. CA3
- C. CA2
- D. CA4
Explanation: If r is proportional to C_A^n, doubling concentration changes the rate by 2^n.
Correct answer: CA2- A. Very slow
- B. Very fast
- C. Photochemical
- D. Both B. and C.
Explanation: Formation of a latent photographic image is initiated by light, making it a photochemical reaction, and the exposure process is very…
Correct answer: Both B. and C.- A. 0
- B. 0.5
- C. 1
- D. 2
Explanation: For r proportional to C_A^n, doubling concentration gives 2^n = 2. Hence n = 1, so the reaction is first order in A.
Correct answer: 1- A. Reaction rate
- B. Rate constant
- C. Energy of activation
- D. Frequency factor
Explanation: The Arrhenius relation, k = A exp(-Eₐ/RT), describes how the rate constant changes with temperature.
Correct answer: Rate constant- A. Reactant's concentration
- B. Pressure
- C. Temperature
- D. None of these
Explanation: For a given reaction, the rate constant generally increases with temperature because more molecules can overcome the activation-energy…
Correct answer: Temperature- A. 0
- B. 1
- C. < 1
- D. ∞
Explanation: A CSTR is assumed to be perfectly mixed, so its axial concentration gradient is completely dispersed.
Correct answer: ∞- A. Increases the speed of a
- B. Can either increase or decrease the speed of a
- C. Decreases the speed of a
- D. Alters the value of equilibrium constant in a reversible
Explanation: A catalyst changes reaction speed by providing an alternative pathway with a different activation energy, and it may either accelerate or…
Correct answer: Can either increase or decrease the speed of a3676. The equilibrium constant of a catalytic chemical reaction _______________ due to the presence of?
- A. Remain unaffected
- B. Increases
- C. Decreases
- D. a catalyst.
- E. Unpredictable from the data
Explanation: A catalyst changes the rates of forward and reverse reactions without changing their thermodynamic balance.
Correct answer: Remain unaffected- A. d(VCA)/dt = -F (CAF - CA) - kCA2V
- B. d(VCA)/dt = F (CAF - CA) - kCA2V
- C. d(VCA)/dt = -FCA - kCA2V
- D. d(VCA)/dt = FCAF - kCA2V
Explanation: With no outlet stream, A enters at F C_AF and is consumed at kC_A²V. Thus accumulation equals feed minus reaction consumption: d(VC_A)/dt…
Correct answer: d(VCA)/dt = FCAF - kCA2V- A. Catalyst size is reduced or the catalyst diffusivity is increased
- B. Catalyst size is reduced or the catalyst diffusivity is reduced
- C. Catalyst size is increased or the catalyst diffusivity is reduced
- D. Catalyst size is increased or the catalyst diffusivity is increased
Explanation: Effectiveness improves when internal diffusion resistance decreases. Reducing catalyst size shortens the diffusion path, while increasing…
Correct answer: Catalyst size is reduced or the catalyst diffusivity is increased- A. Catalyst
- B. Number of molecules of reactants taking part in the reaction
- C. Reactant's concentration
- D. Temperature
Explanation: Reaction rate is governed by factors such as reactant concentration, temperature and catalytic effects, not by simply counting the…
Correct answer: Number of molecules of reactants taking part in the reaction- A. Solid density
- B. Pore volume
- C. Surface area
- D. All A., B. and C.
Explanation: The BET adsorption method measures the specific surface area of a porous solid from the amount of gas adsorbed.
Correct answer: Surface area