15. For the reaction . Therefore, the reaction under standard conditions is
(A) spontaneou us only at temperatures between 10 K and 800 K
(B) spontaneous at temperatures greater than 800 K
(C) spontaneous at all temperatures
(D) nonspontaneous at all temperatures
(E) spontaneous at temperatures less than 10 K

11. A 100.0-mL sample of 0.2 M (CH3)3N is titrated with 0.2 M HCI. What is the pH at the equivalence point? (A) 5.4 (B)7.0 (C) 10.3 (D) 3.1 (E) 9.9

12. You have a solution of 0.10 M CI- and 0.10 M . You add 0.10 M silver nitrate dropwise into the solution. . Which of the following will precipitate first? (A) silver nitrate (B) silver chromate (C) cannot be determined from the information given (D) silver chloride (E) none of these

13. A 0.012-mol sample of Na:SO, is added to 400 mL of each of two solutions. One solution contains 1.5 x 103 M BaCh； the other contains for CaSO, = 6.1 x 10S. Which of the following statements is true? (A) both BaSO4, and CaSO4 would precipitate (B) not enough information is given to determine whether precipitation would occur (C) CaSO4 , would precipitate, but BaSO4, would not (D) BaSO4, would precipitate but  CaSO4  would not (E) neither BaSO4, nor  CaSO4 , would precipitate.

14. is_________for exothermic reactions and_________ for endothermic reactions. (A) favorable, unfavorable (B) favorable, favorable (C) unfavorable, favorable (D) unfavorable, unfavorable (E) cannot tell

16. When a battery dies, which of the following is true? (A)△G° = 0 (B)△G = O (C) E°= O (D) Q= 1 (E) A and C

17. Which of the following statements is/are true of the electrolysis of brine? I: chlorine is produced at the anode of the cell during the electrolysis of brine；Il: under normal circumstances, sodium is produced at the cathode of the cell during the electrolysis of brine； III: hydrogen is produced at the cathode of the cell during the electrolysis of brine. (A) I only (B) II only (C) III only (D) I and II (E) I and Ill

18. How many f orbitals have the value n = 3? (A) 3(B) 1 (C)0(D) 5(E)7

19. How many unpaired electr rons does cobalt have in its ground state? (A) 7 (B) 27 (C) 5 (D)3 (E)1

20. Which of the following exhibits the correct orders (increasing) for atomic radius and ionization energy, respectively? (A) F, S, O, and O, S, F (B) F, O, s, and s, O, F (C) s, O, F, and F, O, s (D) S, F, O, and S, F, O (E) none of these

21. Draw the Lewis structures of the molecules below, and use them to answer the following questions. How many of the molecules have no dipole moment? BH3, NO2, SF6, O3 and PCl5 (A) 2 (B) 4 (C) 1 (D) 3 (E) they are all polar.