Unit 8: Chemical Reactivity
Difficult MCQs (Continued)
- What happens to the equilibrium constant when the temperature of an exothermic reaction is increased?
- A) It increases
- B) It decreases
- C) It remains constant
- D) It becomes zero
- Answer: B) It decreases
- Which of the following would increase the rate of a reaction involving a solid reactant?
- A) Decreasing the surface area
- B) Increasing the temperature
- C) Using a less reactive catalyst
- D) Decreasing the pressure
- Answer: B) Increasing the temperature
- What is the term for the equilibrium constant expression for a reaction that is written with gases only?
- A) Equilibrium constant
- B) Reaction quotient
- C) Gas-phase equilibrium constant
- D) Partial equilibrium constant
- Answer: C) Gas-phase equilibrium constant
- Which of the following statements about the reaction rate is incorrect?
- A) The rate of reaction can be determined experimentally.
- B) The rate of reaction is constant throughout the reaction.
- C) The rate of reaction can be affected by temperature.
- D) The rate of reaction can be influenced by the presence of a catalyst.
- Answer: B) The rate of reaction is constant throughout the reaction.
- Which of the following factors does not affect the reaction mechanism?
- A) Temperature
- B) Pressure
- C) Concentration of reactants
- D) Catalyst
- Answer: B) Pressure
- What is the effect of a catalyst on the Gibbs free energy of a reaction?
- A) It decreases the Gibbs free energy
- B) It increases the Gibbs free energy
- C) It does not affect the Gibbs free energy
- D) It changes the Gibbs free energy to zero
- Answer: C) It does not affect the Gibbs free energy
- In the context of chemical reactivity, what does the term “rate-determining step” refer to?
- A) The step that involves the most reactants
- B) The slowest step in a reaction mechanism
- C) The fastest step in a reaction mechanism
- D) The step that produces the most products
- Answer: B) The slowest step in a reaction mechanism
- Which of the following best describes the effect of a catalyst on the overall enthalpy change of a reaction?
- A) It increases the enthalpy change
- B) It decreases the enthalpy change
- C) It does not affect the enthalpy change
- D) It changes the enthalpy change to zero
- Answer: C) It does not affect the enthalpy change
- What is the effect of a catalyst on the equilibrium constant of a reaction?
- A) It changes the equilibrium constant
- B) It increases the equilibrium constant
- C) It decreases the equilibrium constant
- D) It does not affect the equilibrium constant
- Answer: D) It does not affect the equilibrium constant
- Which of the following is true for a reaction that has a negative ΔG?
- A) The reaction is non-spontaneous.
- B) The reaction is at equilibrium.
- C) The reaction is spontaneous.
- D) The reaction is endothermic.
- Answer: C) The reaction is spontaneous.