Catalysis MCQs

1. What is a catalyst? a) A substance that is consumed during a reaction b) A substance that increases the rate of a chemical reaction without being consumed c) A substance that decreases the rate of a chemical reaction d) A substance that changes the equilibrium position of a reaction Answer: b) A substance that increases the rate of a chemical reaction without being consumed 2. What is the main role of a catalyst in a chemical reaction? a) To change the equilibrium position of the reaction b) To increase the activation energy of the reaction c) To decrease the activation energy of the reaction d) To be consumed in the reaction Answer: c) To decrease the activation energy of the reaction 3. Which type of catalyst is used in heterogeneous catalysis? a) A liquid catalyst b) A solid catalyst c) A gas catalyst d) A solution catalyst Answer: b) A solid catalyst 4. What is an enzyme? a) A non-biological catalyst b) A biological catalyst c) A type of inhibitor d) A reactant in a chemical reaction Answer: b) A biological catalyst 5. What is the effect of a catalyst on the equilibrium position of a reaction? a) It shifts the equilibrium position to favor products b) It shifts the equilibrium position to favor reactants c) It does not affect the equilibrium position d) It makes the reaction irreversible Answer: c) It does not affect the equilibrium position 6. Which term describes a catalyst that participates in the reaction but is regenerated at the end? a) Poison b) Inhibitor c) Homogeneous catalyst d) Heterogeneous catalyst Answer: c) Homogeneous catalyst 7. What is a catalytic converter used for in automobiles? a) To increase fuel efficiency b) To decrease the rate of exhaust emission reactions c) To convert harmful gases into less harmful substances d) To cool the engine Answer: c) To convert harmful gases into less harmful substances 8. What is the primary function of a catalyst in an industrial process? a) To increase the reaction rate b) To change the reaction yield c) To reduce the cost of raw materials d) To increase the temperature of the reaction Answer: a) To increase the reaction rate 9. Which type of catalysis involves a catalyst that is in the same phase as the reactants? a) Heterogeneous catalysis b) Homogeneous catalysis c) Enzyme catalysis d) Surface catalysis Answer: b) Homogeneous catalysis 10. What is a catalyst poison? a) A substance that enhances the activity of a catalyst b) A substance that inhibits or reduces the effectiveness of a catalyst c) A substance that regenerates a catalyst d) A substance that accelerates the reaction rate Answer: b) A substance that inhibits or reduces the effectiveness of a catalyst 11. What term describes the process of using a catalyst in a chemical reaction where the catalyst is in a different phase than the reactants? a) Heterogeneous catalysis b) Homogeneous catalysis c) Biocatalysis d) Autocatalysis Answer: a) Heterogeneous catalysis 12. What is the primary difference between homogeneous and heterogeneous catalysis? a) The size of the catalyst b) The phase of the catalyst relative to the reactants c) The temperature of the reaction d) The pressure of the reaction Answer: b) The phase of the catalyst relative to the reactants 13. What is an autocatalyst? a) A catalyst that speeds up a reaction without being involved in the reaction b) A catalyst that is regenerated at the end of the reaction c) A substance that catalyzes its own formation d) A substance that inhibits its own reaction Answer: c) A substance that catalyzes its own formation 14. Which of the following is an example of a heterogeneous catalyst? a) Acid in aqueous solution b) Platinum in catalytic converters c) Enzyme in biological reactions d) Hydrochloric acid in a reaction Answer: b) Platinum in catalytic converters 15. What does a catalyst do to the activation energy of a reaction? a) Increases it b) Decreases it c) Has no effect on it d) Makes it variable Answer: b) Decreases it 16. What is a typical characteristic of enzyme catalysts? a) They are not specific to their substrates b) They operate at very high temperatures c) They are highly specific to their substrates d) They are not affected by pH changes Answer: c) They are highly specific to their substrates 17. What is the role of a catalyst in the Haber process for ammonia synthesis? a) To increase the pressure of the reaction b) To increase the temperature of the reaction c) To speed up the formation of ammonia d) To absorb excess nitrogen Answer: c) To speed up the formation of ammonia 18. In which type of catalysis is the catalyst usually a metal or metal oxide? a) Homogeneous catalysis b) Heterogeneous catalysis c) Enzyme catalysis d) Acid-base catalysis Answer: b) Heterogeneous catalysis 19. What is a catalytic cycle? a) The process of a catalyst being consumed and regenerated b) The sequence of steps in which a catalyst participates in a reaction c) The time it takes for a catalyst to start working d) The temperature range in which a catalyst is effective Answer: b) The sequence of steps in which a catalyst participates in a reaction 20. How does a catalyst affect the rate of a reaction? a) It slows down the reaction rate b) It has no effect on the reaction rate c) It changes the reaction mechanism d) It increases the reaction rate Answer: d) It increases the reaction rate 21. What is the main advantage of using a catalyst in industrial processes? a) It lowers the cost of raw materials b) It increases the energy requirements of the process c) It decreases the overall cost of the process by increasing reaction rates d) It changes the physical state of the products Answer: c) It decreases the overall cost of the process by increasing reaction rates 22. What type of reaction is typically catalyzed by an acid or base? a) Redox reactions b) Hydrolysis reactions c) Combustion reactions d) Decomposition reactions Answer: b) Hydrolysis reactions 23. What is a zeolite? a) A type of metal catalyst b) A type of enzyme c) A microporous, aluminosilicate mineral used as a catalyst d) A type of organic molecule that acts as a catalyst Answer: c) A microporous, aluminosilicate mineral used as a catalyst 24. What is the function of a promoter in catalysis? a) To inhibit the catalyst b) To enhance the effectiveness of a catalyst c) To act as a catalyst itself d) To replace the catalyst Answer: b) To enhance the effectiveness of a catalyst 25. What happens to the catalyst at the end of a chemical reaction? a) It is permanently changed b) It is consumed and lost c) It is regenerated and remains unchanged d) It becomes part of the products Answer: c) It is regenerated and remains unchanged 26. Which term refers to a substance that decreases the activity of a catalyst? a) Activator b) Inhibitor c) Regenerator d) Promoter Answer: b) Inhibitor 27. What is the role of a catalyst in the decomposition of hydrogen peroxide? a) To speed up the decomposition reaction b) To slow down the decomposition reaction c) To change the color of the solution d) To produce oxygen gas directly Answer: a) To speed up the decomposition reaction 28. In enzyme catalysis, what is the term for the molecule that the enzyme acts upon? a) Catalyst b) Substrate c) Product d) Inhibitor Answer: b) Substrate 29. What is a key feature of a catalytic reaction? a) The catalyst is permanently altered by the reaction b) The catalyst is consumed in the reaction c) The catalyst remains unchanged after the reaction d) The catalyst changes the products of the reaction Answer: c) The catalyst remains unchanged after the reaction 30. What is a key difference between enzyme catalysis and chemical catalysis? a) Enzymes are less specific than chemical catalysts b) Enzymes are typically used in non-biological reactions c) Enzymes operate under mild conditions compared to chemical catalysts d) Chemical catalysts are usually more specific than enzymes Answer: c) Enzymes operate under mild conditions compared to chemical catalysts