Unit 8: Chemical Reactivity
- Which of the following is true about the activation energy of a reaction?
- A) It is the energy required to reach the transition state.
- B) It is the energy released during the reaction.
- C) It is the energy of the products.
- D) It is the difference between the energy of the reactants and products.
- Answer: A) It is the energy required to reach the transition state.
- What is the effect of a catalyst on the reaction mechanism?
- A) It introduces a new intermediate.
- B) It increases the activation energy.
- C) It changes the enthalpy of the reaction.
- D) It decreases the activation energy by providing an alternative pathway.
- Answer: D) It decreases the activation energy by providing an alternative pathway.
- In the reaction A + B → C, if the reaction is second-order with respect to A and first-order with respect to B, what is the overall reaction order?
- A) Zero-order
- B) First-order
- C) Second-order
- D) Third-order
- Answer: D) Third-order
- Which of the following best describes the equilibrium constant K?
- A) It is dependent on the concentration of reactants and products.
- B) It changes with the pressure of the reaction system.
- C) It varies with temperature but not with pressure.
- D) It is affected by the presence of a catalyst.
- Answer: C) It varies with temperature but not with pressure.
- What is the impact of increasing the concentration of a reactant on the rate of reaction if the reaction is zero-order with respect to that reactant?
- A) The rate of reaction increases.
- B) The rate of reaction decreases.
- C) The rate of reaction remains constant.
- D) The rate of reaction becomes zero.
- Answer: C) The rate of reaction remains constant.
- What does the rate constant (k) of a reaction depend on?
- A) Concentration of reactants
- B) Temperature
- C) Pressure
- D) Catalyst
- Answer: B) Temperature
- Which of the following factors does not affect the equilibrium constant of a reaction?
- A) Temperature
- B) Pressure
- C) Concentration of reactants
- D) Presence of a catalyst
- Answer: D) Presence of a catalyst
- What happens to the reaction rate when the temperature is increased for an exothermic reaction?
- A) The reaction rate decreases.
- B) The reaction rate remains constant.
- C) The reaction rate increases.
- D) The reaction rate becomes zero.
- Answer: C) The reaction rate increases.
- Which of the following is true for a reaction with a rate constant of 2.5 L^2/mol^2s?
- A) The reaction is second-order.
- B) The reaction is first-order.
- C) The reaction is zero-order.
- D) The reaction is third-order.
- Answer: A) The reaction is second-order.