Chemical Reaction Engineering – Multiple Choice Questions (MCQs)

1. 25. What is 'selectivity' in multiple reactions?

   • A. The ratio of the rate of formation of the desired product to the rate of formation of undesired products
   • B. The overall conversion
   • C. The efficiency of the catalyst
   • D. The amount of byproduct formed

2. 26. What is 'parallel reactions'?

   • A. Reactions where reactants consume simultaneously to form different products
   • B. Reactions that occur in sequence
   • C. Reactions that require a catalyst
   • D. Reactions that form only one product

3. 27. What is 'series reactions' (or consecutive reactions)?

   • A. Reactions where products of one reaction become reactants for a subsequent reaction
   • B. Reactions that occur simultaneously
   • C. Reactions that produce only one product
   • D. Reactions that do not involve intermediate species

4. 28. What is 'optimum temperature progression' in a reactor?

   • A. Varying the temperature along the reactor length to maximize conversion or selectivity
   • B. Maintaining a constant temperature
   • C. Operating at the highest possible temperature
   • D. Operating at the lowest possible temperature

5. 29. What is 'fluidized bed reactor' (FBR)?

   • A. A reactor where a solid catalyst is suspended in a fluid by the upward flow of gas or liquid
   • B. A reactor with a fixed catalyst bed
   • C. A reactor used for homogeneous reactions
   • D. A reactor with no solid particles

6. 30. What is 'packed bed reactor' (PBR)?

   • A. A reactor containing a fixed bed of solid catalyst particles through which fluids flow
   • B. A reactor with suspended solid particles
   • C. A reactor used for homogeneous reactions
   • D. A reactor with no solid catalyst

7. 31. What is 'residence time distribution' (RTD)?

   • A. A measure of the time that fluid elements spend in a reactor
   • B. A measure of reaction rate
   • C. A measure of reactor volume
   • D. A measure of fluid viscosity

8. 32. What is 'segregation model' in non-ideal flow reactors?

   • A. A model that assumes fluid elements retain their identities (do not mix at the molecular level) and react independently
   • B. A model that assumes complete mixing at the molecular level
   • C. A model for ideal reactors
   • D. A model that only applies to batch reactors

9. 33. What is 'maximum mixedness model' in non-ideal flow reactors?

   • A. A model that assumes fluid elements achieve the maximum possible degree of mixing at the molecular level at each point in the reactor
   • B. A model that assumes no mixing at the molecular level
   • C. A model for ideal reactors
   • D. A model that only applies to PFRs

10. 34. What is the 'effectiveness factor' (η) in heterogeneous catalysis?

    • A. The ratio of the actual reaction rate to the rate that would occur if the catalyst pellet interior were at the same concentration as the pellet surface
    • B. The selectivity of the reaction
    • C. The conversion of the reaction
    • D. The catalyst surface area

11. 35. What is 'Thiele modulus' (Φ_n)?

    • A. A dimensionless group that compares the reaction rate to the diffusion rate within a catalyst pellet
    • B. A dimensionless group for fluid flow
    • C. A dimensionless group for heat transfer
    • D. A dimensionless group for mass transfer

12. 36. What does a small Thiele modulus indicate?

    • A. Reaction rate is limited by diffusion
    • B. Reaction rate is not limited by diffusion (kinetically controlled)
    • C. High effectiveness factor
    • D. Low effectiveness factor