66. Consider the following reaction:

A₂ + B2 → 2AB       △H = –235 kJ

The bond energy for A₂ is half the amount of AB. The bond energy of B₂ = 247 kJ/mol. What is the bond energy of A2?
(A) 482 kJ/mol
(B) 238 kJ/mol
(C) 161 kJ/mol
(D) –118 kJ/mol
(E) –129 kJ/mol

62. Solid KF has a lattice energy of –804 kJ/mol and a heat of solution (in water) of –15 kJ/mol. RbF has a lattice energy of –768 kJ/mol and a heat of solution (in water) of –24 kJ/mol. Which salt forms stronger attractions with water? (A) KF, because it releases more heat during the formation of crystal. (B) KF, because it has a more negative heat of hydration. (C) RbF, because it releases more heat during the formation of crystal. (D) RbF, because it has a more negative heat of hydration. (E) Both salts have the same interactions with water.

【已刪除】63. The reaction 2NO2 → 2NO + O2 obeys the rate law at 400 K. If the initial concentration of NO2 is 1.00 M, how long will it take for the [NO2] to decrease to 0.25 M ? (A) 50 s (B) 100 s (C) 200 s (D) 300 s (E) 600 s

64. Today’s automatic sunglasses utilize the following rearrangement reaction between A and B promoted by UV:However, infrared spectroscopy is often applied to differentiate A and B because of the strong and distinct absorption of _________ functional group.(A) arene (B) conjugated olefin (C) carbonyl (D) ether (E) amide

65. Water desalination is a method to solve the problem of drought resulting from climate change. What is the minimum pressure needed to purify the water from 0.05 M of NaCl(aq) by reverse osmosis at 27 °C? (R = 0.08206 L atm K-1 mol-1 ) (A) 1.23 atm (B) 2.46 atm (C) 3.71 atm (D) 4.52 atm (E) None of the above.

67. Which statement is correct? (A) The bond order of He2 + is 1. (B) The bond order of Ne2 is 1. (C) The bond order of C2 + is 1. (D) N2 has a larger bond order than N2 2– . (E) None of the above.

68. You mix 265.0 mL of 1.20 M lead(II) nitrate with 300.0 mL of 1.55 M potassium iodide. Which of the followings is true? (A) Lead nitrate is the limited reagent. (B) The final concentration of Pb2+ ions is 0.56 M. (C) The final concentration of K+ is 0.823 M. (D) The final concentration of NO3 – is 0.823 M. (E) The final concentration of I– is 0.823 M.

69. Follow the balanced equation: N2(g) + 3H2(g) → 2NH3(g)An equal number of moles of nitrogen and hydrogen gases were added in a balloon. The volume of the balloon is 2.00 L before any reaction occurs. Determine the volume of the balloon after the reaction is complete, assuming constant temperature. (A) 0.67 L (B) 1.00 L (C) 1.33 L (D) 2.00 L (E) 4.00 L

70. One beaker has 75.0 mL of a 2.00 M solution of Na2CrO4(aq). Another one has 125 mL of a 2.00 M solution of AgNO3(aq). Please calculate the concentration of Ag+ after the two solutions are mixed together. (A) 0.00 M (B) 0.02 M (C) 0.75 M (D) 1.25 M (E) 0.50 M

71. Four identical 1.0 L flasks contain the gases He, Cl2, CH4, and NH3, each at 0 °C and 1 atm pressure. Which of the following statements is true? (A) He gas has the smallest average kinetic energy. (B) Cl2 gas has the highest density. (C) CH4 gas has the greatest number of molecules. (D) NH3 gas molecules collide elastically. (E) All gas molecules have same average velocity.

72. The valve between the 3.00 L bulb, in which the gas pressure is 2.00 atm, and the 2.00 L bulb, in which the gas pressure is 2.70 atm, is opened. What is the final pressure in the two bulbs, assuming the temperature remains constant?(A) 0.71 atm (B) 1.03 atm (C) 1.62 atm (D) 2.01 atm (E) 2.28 atm