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 170 of 350
- 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 CA3388. 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- A. 1.5 K
- B. 2.5 K
- C. 0.693/K
- D. 6.93 K
Explanation: For a first-order reaction, the half-life is independent of the initial concentration and is given by t₁/₂ = ln 2/k = 0.693/k.
Correct answer: 0.693/K- A. None of these
- B. Increases the activation energy
- C. Decreases the molecular collision diameter
- D. Decreases the energy barrier for reaction
Explanation: A catalyst provides an alternative reaction pathway with a lower activation-energy barrier, allowing more molecules to react per unit…
Correct answer: Decreases the energy barrier for reaction- A. k KAKB pApB / (1 + KApA + KBpB + KCpC)2
- B. k KAKB pApB / (1 + KApA + KBpB)
- C. k KAKB pApB / (1 + KApA + KBpB + KCpC)
- D. k KA pApB / (1 + KApA + KBpB)
Explanation: With competitive adsorption, the surface coverages of adsorbed A and B are proportional to K_Ap_A and K_Bp_B, while the vacant-site…
Correct answer: k KAKB pApB / (1 + KApA + KBpB + KCpC)2- A. 2
- B. 4
- C. 11
- D. 22
Explanation: For a second-order reaction, t = X/[kC_A0(1−X)]. Thus t₉₀/t₄₅ = [0.90/0.10]/[0.45/0.55] = 11, giving the required ratio.
Correct answer: 11- A. Accompanied with emission of light
- B. Catalysed by light
- C. Initiated by light
- D. All A., B. & C.
Explanation: A photochemical reaction is initiated when reactant molecules absorb light and acquire enough energy to react.
Correct answer: Initiated by light- A. Fixed
- B. Fluidised
- C. Fixed bed reactor followed by a fluidised
- D. Fluidised bed reactor followed by a fixed
Explanation: A fluidised bed provides effective heat removal and limits temperature rise in a highly exothermic reaction, while the following fixed bed…
Correct answer: Fluidised bed reactor followed by a fixed- A. Is at the highest allowable temperature throughout
- B. Increases
- C. Decreases
- D. First increases and then decreases
Explanation: For an endothermic reversible reaction, increasing temperature generally increases both the reaction rate and the equilibrium conversion.
Correct answer: Is at the highest allowable temperature throughout- A. Suitable for gas-phase reactions on commercial scale
- B. Suitable for liquid phase reactions involving small production rate
- C. Least expensive to operate for a given rate
- D. Most suitable for very large production rate
Explanation: Batch reactors are commonly used for liquid-phase products made at relatively small or moderate production rates, especially when…
Correct answer: Suitable for liquid phase reactions involving small production rate- A. Third
- B. Second
- C. First
- D. Zero
Explanation: Radioactive decay is a first-order process because the decay rate is proportional to the amount of radioactive material remaining.
Correct answer: First- A. Tank in series
- B. Dispersion
- C. Neither A. nor B.
- D. Both A. & B.
Explanation: Both the tanks-in-series model and the dispersion model describe non-ideal flow using one adjustable parameter, such as the number of…
Correct answer: Both A. & B.- A. The energy of reacting molecules exceeds the activation energy by absorption of light
- B. It is an exothermic reaction
- C. It is a reversible reaction
- D. None of these
Explanation: Absorption of light supplies the reacting molecules with energy directly, often raising them above the activation-energy barrier.
Correct answer: The energy of reacting molecules exceeds the activation energy by absorption of light- A. Achieving cent percent conversion of reactants into products
- B. Liquid phase reactions
- C. Large scale gaseous phase reactions
- D. Obtaining uniform polymerisation products in highly exothermic reactions
Explanation: Batch reactors are widely used for liquid-phase reactions because they offer flexible operation and can handle relatively small production…
Correct answer: Liquid phase reactions