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. Dehydrogenation of lower paraffins
- B. Dehydrogenation of Naphthene
- C. Dehydrocyclization of higher paraffins
- D. Isomerisation of paraffins
Explanation: Catalytic reforming favorably dehydrogenates naphthenes, dehydrocyclizes suitable paraffins and isomerizes hydrocarbons to raise octane…
Correct answer: Dehydrogenation of lower paraffins- A. 10 atm & 500°C
- B. 2 atm & 500°C
- C. 30 atm & 200°C
- D. 50 atm & 750°C
Explanation: Fluid catalytic cracking commonly uses temperatures near 500°C and relatively low pressures, around 1–3 atm, because cracking is favoured…
Correct answer: 2 atm & 500°C- A. Gasoline obtained has a very low octane number
- B. Pressure & temperature is very high
- C. Gasoline obtained has very high amount of gum forming compounds
- D. Gasoline obtained has very high aromatic content
Explanation: Catalytic cracking promotes dehydrogenation, cyclisation and aromatisation, so its gasoline generally has a high octane number and…
Correct answer: Gasoline obtained has very high aromatic content- A. Non-elementary
- B. Multiple
- C. Autocatalytic
- D. Elementary
Explanation: For an elementary reaction, the rate equation follows directly from the stoichiometric equation.
Correct answer: Non-elementary- A. Is independent of temperature
- B. Both B. and C.
- C. Depends on the nature of the reactants
- D. Varies with temperature
Explanation: The rate constant changes with temperature according to the Arrhenius relationship and also depends on the reacting species and reaction…
Correct answer: Both B. and C.- A. 1
- B. 2
- C. 3
- D. 4
Explanation: For a second-order reaction, the time required for a fixed fractional conversion is proportional to 1/C₀.
Correct answer: 2- A. Nature of the reactants
- B. Concentration of the reactants
- C. Temperature at which the reaction is carried
- D. All A., B. and C.
Explanation: Reaction velocity is affected by the chemical nature of the reactants, their concentrations, and temperature.
Correct answer: All A., B. and C.- A. Catalytic cracking
- B. Methanol synthesis
- C. Ammonia synthesis
- D. Oxidation of sulphur
Explanation: Catalytic cracking requires heat to break large hydrocarbon molecules into smaller ones, so it is endothermic.
Correct answer: Catalytic cracking- A. 5°C
- B. 10°C
- C. 20°C
- D. 100°C
Explanation: At 50% conversion, heat released is 0.5 kJ per mole initially present. The adiabatic temperature rise is ΔT = 0.5/0.050 = 10 K, which is…
Correct answer: 10°C- A. Series of CSTR
- B. Plug flow reactor
- C. Backmix reactor
- D. PFR in series
Explanation: When high reactant concentration improves yield, backmixing is undesirable because a CSTR operates throughout at the lower exit…
Correct answer: Backmix reactor- A. 100
- B. 97.5
- C. 95
- D. 2.5
Explanation: Formation of 95 kmol/h ethylene consumes 95 kmol/h ethanol, while 2.5 kmol/h diethyl ether consumes 5 kmol/h ethanol.
Correct answer: 100- A. Mixing takes place in axial direction only
- B. Residence time is constant
- C. Condition similar to plug flow reactor exists
- D. Velocity of reaction can be controlled
Explanation: A semi-batch reactor permits controlled addition or removal of reactants during operation, so the reaction rate can be adjusted through…
Correct answer: Velocity of reaction can be controlled- A. All A., B. and C.
- B. Agglomeration of metal particles caused by thermal sintering of the solid surface
- C. Covering of the catalytic active sites by a foreign substance
- D. Loss in surface area of the active component
Explanation: Catalyst deactivation can result from loss of active surface area, thermal sintering or agglomeration of metal particles, and poisoning by…
Correct answer: All A., B. and C.- A. 0
- B. 1
- C. 2
- D. 3
Explanation: For an nth-order reaction, k has units of concentration^(1−n) per time.
Correct answer: 2- A. 4
- B. 1/2
- C. 2
- D. 1/4
Explanation: At the boundary between initial increase and decrease of B, its initial rate is zero: k₁C_A0² = k₂C_B0².
Correct answer: 1/4- A. 0.5
- B. 1
- C. 2
- D. 3
Explanation: For A → 3B, one mole of A becomes three total moles, and at constant temperature and pressure gas volume is proportional to total moles.
Correct answer: 2- A. 0
- B. 1
- C. 2
- D. 3
Explanation: Doubling concentration changes the rate by 2^n. Because the rate doubles, 2^n = 2, giving n = 1 and hence a first-order dependence on P.
Correct answer: 1- A. Pressure
- B. Concentration of reactants
- C. Temperature
- D. Duration of reaction
Explanation: The Arrhenius equation, k = A exp(−E_a/RT), shows that increasing temperature raises the rate constant, so lowering temperature decreases…
Correct answer: Temperature- A. (CA/2)n
- B. (½)n CA
- C. (CA/2)1/n
- D. (CA)1/2n
Explanation: Each half-life multiplies the remaining amount by 1/2, so after n half-lives the amount is C_A(1/2)^n.
Correct answer: (½)n CA80. In an exothermic chemical reaction, the reactants compared to the products have__________________?
- A. More energy
- B. Higher temperature
- C. Less energy
- D. Same energy
Explanation: An exothermic reaction releases energy, so the products lie at a lower energy level than the reactants.
Correct answer: More energy