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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395 questions · page 15 of 20
- A. 4
- B. 16
- C. 8
- D. 2
Explanation: With the same reactant amounts and temperature, reducing the volume to one-fourth makes both concentrations four times larger.
Correct answer: 16- A. Neither A. nor B.
- B. Concentration
- C. Both A. & B.
- D. Reaction rate
Explanation: At steady state, an ideal CSTR is perfectly mixed and its concentration and reaction rate remain constant with time.
Correct answer: Neither A. nor B.283. The enzyme which can catalyse the conversion of glucose to ethyl alcohol is ___________________?
- A. Invertase
- B. Zymase
- C. Diastase
- D. Maltase
Explanation: Zymase is the enzyme complex in yeast that converts glucose into ethanol and carbon dioxide during alcoholic fermentation.
Correct answer: Zymase- A. Initial concentration of reactants
- B. Time of reaction
- C. Temperature of the system
- D. Extent of reaction
Explanation: The rate constant is primarily determined by temperature through the Arrhenius relation k = A exp(-Ea/RT).
Correct answer: Temperature of the system- A. 0
- B. 1
- C. 1.5
- D. 2
Explanation: In a batch reactor, a linear increase of conversion with time means dX/dt is constant.
Correct answer: 0- A. Constant fluid density systems
- B. Variable fluid density systems
- C. Non-isothermal gas reaction
- D. Gas reactions with changing number of moles
Explanation: Space time is V divided by the inlet volumetric flow rate, whereas holding time uses the actual flow rate inside the reactor.
Correct answer: Constant fluid density systems287. For a zero order reaction, the concentration of product increases with the _____________________?
- A. Total pressure
- B. Increase in initial concentration
- C. Increase of reaction time
- D. Decrease in total pressure
Explanation: For a zero-order reaction, the product formation rate is constant, so product concentration increases linearly with reaction time.
Correct answer: Increase of reaction time- A. 2/3
- B. 3/8
- C. 1/3
- D. 5/8
Explanation: For 2A ⇌ B, the total moles decrease as A reacts, giving ε = −0.8/2 = −0.4. At X = 0.5, CA/CA0 = (1 − X)/(1 + εX) = 0.5/0.8 = 5/8.
Correct answer: 5/8- A. Temperature should be high in the beginning and decreased towards the end of the reaction
- B. Very low temperature should be used throughout the reaction
- C. Very high temperature should be used throughout the reaction
- D. None of these
Explanation: For an exothermic reversible reaction, high temperature is useful near the inlet for rapid reaction, but temperature should fall toward…
Correct answer: Temperature should be high in the beginning and decreased towards the end of the reaction- A. Zero
- B. First
- C. Second
- D. Third
Explanation: If the rate depends on only one concentration raised to the first power, the reaction is first order.
Correct answer: First291. When a catalyst increases the rate of chemical reaction, the rate constant_____________________?
- A. Decreases
- B. Remain constant
- C. Increases
- D. Become infinite
Explanation: A catalyst provides an alternative pathway with lower activation energy, so at the same temperature its effective rate constant is higher.
Correct answer: Increases- A. Lose a proton
- B. None of these
- C. Gain an electron
- D. Gain a proton
Explanation: A Brønsted base accepts a proton, so base catalysis is associated with substances having a tendency to gain H+.
Correct answer: Gain a proton- A. Non-Homogeneous
- B. Homogeneous
- C. Heterogeneous
- D. Non-Heterogeneous
Explanation: Thermal cracking of gas oil proceeds without a solid catalyst and is treated as a homogeneous gas-phase radical reaction.
Correct answer: Homogeneous- A. Moles for med/(surface of catalyst) (time)
- B. Moles formed/volume of reactor) (time)
- C. None of these
- D. Mole formed/volume of catalyst) (time)
Explanation: Reaction rate may be expressed per reactor volume, catalyst volume, or catalyst surface area, provided the basis is stated.
Correct answer: None of these- A. Consecutive
- B. Third order
- C. Zero order
- D. None of these
Explanation: In a zero-order reaction, the rate is k and does not depend on reactant concentration.
Correct answer: Zero order- A. Poor product quality control
- B. High labour and handling cost
- C. High shutdown time requirement for emptying, cleaning and refilling
- D. All A., B. and C.
Explanation: Batch operation can cause batch-to-batch quality variation and requires substantial labour, handling, and downtime for emptying, cleaning…
Correct answer: All A., B. and C.- A. Variation in extent of reaction and properties of the reaction mixture with time
- B. Constant residence time
- C. Variation in reactor volume
- D. Very low conversion
Explanation: In a batch reactor, reactants are charged initially and their concentrations, conversion, and other mixture properties change with time.
Correct answer: Variation in extent of reaction and properties of the reaction mixture with time- A. k. t = ln a/(a - x)
- B. k. t = x/a (a - x)
- C. k. t = ln (a - x)/a
- D. k. t = ln a (a - x)/x
Explanation: For a first-order reaction, integration of −dC/dt = kC from C = a to C = a−x gives kt = ln[a/(a−x)].
Correct answer: k. t = ln a/(a - x)- A. Less than
- B. Equal to
- C. More than
- D. Equal to or more than
Explanation: Molecules must have energy at least equal to the activation energy to cross the reaction-energy barrier, so the condition is equal to or…
Correct answer: Equal to or more than- A. Diffusion through ash layer
- B. Film diffusion
- C. Chemical reaction
- D. Either A., B. or C.
Explanation: For the shrinking-core model, resistance through the ash layer gives a characteristic time proportional to the square of particle…
Correct answer: Diffusion through ash layer