7. Calculate the AG value for a reaction with AH = -20 kJ/mol and AS = 50 J/(mol-K) at 298 K. a)-6.67 kJ/mol b)-16.67 kJ/mol c) 6.67 kJ/mol d) 16.67 kJ/mol 8. Which of the following conditions would result in a spontaneous reaction? a) AG> 0 and AS > 0 b) AG 0 d) AG >0 and AS < 0 9. The direction of a reaction is determined by: a) The magnitude of AG. b) The sign of AG. c) The value of AH. d) The temperature of the system. 10. A reaction has a AG value of -15 kJ/mol at 298 K. Which statement is true? a) The reaction is non-spontaneous. b) The reaction is spontaneous. c) The reaction is sometimes spontaneous. d) The reaction is at equilibrium. II. True or False: Beside the number, write T if the statement is correct, and F if the statement is false. 11. Gibbs free energy (AG) measures the maximum amount of useful work that can be obtained from a system at constant temperature and pressure. 12. If AG is negative, it indicates that a reaction is spontaneous and can occur without the input of external energy. 13. The equation for calculating Gibbs free energy is AG = AH-TAS, where AH is the enthalpy change and AS is the entropy change. 14. If AG is positive, it means the reaction is non- spontaneous and cannot occur under any conditions. 15. The sign of AG determines the direction of a reaction. If AG is negative, the reaction proceeds in the forward direction. 16. At equilibrium, the value of AG is always zero. 17. The value of AG is independent of temperature. 18. A positive AS value always indicates an increase in disorder or randomness. 19. A decrease in entropy always leads to a decrease in Gibbs free energy. 20. AG can be used to predict the spontaneity and direction of a reaction, but it cannot provide information about the reaction rate.​