67. According to molecular orbital, which of the following molecules is diamagnetic?
(A) HF
(B) O₂
(C) NO
(D)
(E)

63. Please calculate the ΔS if ΔHvap is 66.8 kJ/mol, and the boiling point is 83.4°C at 1 atm, when the substance is vaporized at 1 atm. (A) -187 J/K mol (B) 187 J/K mol (C) 801 J/K mol (D) -801 J/K mol (E) 0

64. Which of the following values is based on the Third Law of Thermodynamics? (A) ΔH°f = 0 for Al(s) at 298 K (B) ΔG°f = 0 for H2(g) at 298 K (C) (D) qsys ＜ 0 for H2O(l) → H2O(s) at 0°C (E) None of these

65. What are the values of bond order belonging to , respectively? (A) 1.5, 2.5 (B) 2.5, 1.5 (C) 2, 3 (D) 3, 2 (E) 2, 2

66. The lattice energy of NaI(s) is -686 kJ/mol, and its heat of solution is -7.6 kJ/mol. Calculate the hydration of energy of NaI(s) in kJ/mol. (A) -678 (B) -694 (C) +678 (D) +694 (E) +15.2

68. Consider the figure, which shows ΔG° for a chemical process plotted against absolute temperature. Which of the following is an incorrect conclusion, based on the information in the diagram? (A) ΔH° ＞ 0 (B) ΔS° ＞ 0 (C) The reaction is spontaneous at high temperatures. (D) ΔS° increases with temperature while ΔH° remains constant. (E) There exists a certain temperature at which ΔH° = TΔS°.

69. Acetone can be easily converted to isopropyl alcohol by addition of hydrogen to the carbonoxygen double bond. Calculate the enthalpy of reaction using the bond energies given.  (A) -484 kJ (B) -366 kJ (C) -48 kJ (D) +48 kJ (E) +366 kJ

70. How many of the following molecules exhibit resonance: , O2F2? (A) 1 (B) 2 (C) 3 (D) 4 (E) 5

71. One mole of X(g) and one mole of Y(g) are mixed in a closed reactor in the presence of catalysts, and Z(g) is generated. The reaction is a X + b Y → c Z, where a, b, and c are the coefficients in the balanced equation. At a certain time, the mixture contains 1.8 moles of gases while the ratio of their partial pressures is PX:PY:PZ = 7:9:2. What are the values of a, b, and c? (A) a = 1, b = 2, c = 3 (B) a = 3, b = 1, c = 2 (C) a = 7, b = 9, c = 2 (D) a = 3, b = 1, c = 8 (E) a = 2, b = 9, c = 7

72. Consider an adiabatic and reversible expansion process from state I to state II. Which of the following statements is true? (A) P1V1 = P2V2 (B)(C) The final temperature will be higher than the initial temperature. (D) The final volume of the gas is much greater than the expansion were carried out isothermally. (E) The work delivered to the surrounding is much smaller than the expansion were carried out isothermally.

73. When a 1.00 mL of the M solution of organic acid is diluted with 9.00 mL of ether, forming solution A and then 2.00 mL of the solution A is diluted with 8.00 mL of ether, forming solution B. What is the concentration of solution B? (A) (B)(C) (D) (E)