68. Which of the shown molecules fits the fragmentation pattern of the mass spectrum below the best?

(A)
(B)
(C)
(D)
(E)

64. How many unpaired electrons are there in an atom of oxygen in its ground state? (A) 1 (B) 2 (C) 4 (D) 0 (E) 3

65. A crystal of NaCl is _____ (A) hard, high-melting, and a poor electrical conductor (B) hard, high-melting, and a good electrical conductor (C) soft, low-melting, and a good electrical conductor (D) soft, high-melting, and a poor electrical conductor (E) soft, low-melting, and a poor electrical conductor

66. Which of the following chemical or physical changes is an endothermic process? (A) the evaporation of water (B) the mixing of sulfuric acid and water (C) the freezing of water (D) the combustion of gasoline (E) none of the above

67. The _____ is the electrode at which the reaction of interest occurs. (A) auxillary electrode (B) counter electrode (C) anode (D) cathode (E) working electrode

69. Which of the following molecules is optically active? (A)(B)(C)(D)(E) none of the above

70. Rank the following compounds according to increasing solubility in water. I CH3-CH2-CH2-CH3 II CH3-CH2-O-CH2-CH3  III CH3-CH2-OH IV CH3-OH (A) I ＜II ＜ IV ＜ III (B) I ＜ III ＜ IV＜ II (C) I ＜II ＜ III ＜ IV (D) III ＜ IV ＜ II ＜ I (E) None of the above is correct.

71. Nitrogen gas (N2) reacts with hydrogen gas (H2) to form ammonia (NH3). At 200°C in a closed container, 1.2 atm of nitrogen gas is mixed with 2.3 atm of hydrogen gas. At equilibrium, the total pressure is 2.1 atm. Calculate the partial pressure of hydrogen gas at equilibrium. (A) 2.3 atm (B) 0.0 atm (C) 1.8 atm (D) 0.20 atm (E) 0.92 atm

72. The corrosion of which transition metal results in a characteristic green patina? (A) lead (B) copper (C) chromium (D) silver (E) iron

73. EDTA is an example of a(n) _____ ligand. (A) hexadentate (B) bidentate (C) octadentate (D) tetradentate (E) tridentate

74. When a molecule absorbs a photon, the molecule is promoted to an excited state M＊. The rate at which M＊ is created is proportional to the concentration of M. There are three pathways that M* may take to return to the ground state. Which statement about these three pathways below is wrong? (A) The rate at which the excited state returns to the ground state is independent of the pathway to the ground state and the concentration of excited state molecules. (B) The three possible pathways to return to the ground state are emission, deactivation, and quenching. (C) Quenching occurs when a second molecule, the quencher Q, collides with M* and energy is transferred from M* to Q: M* + Q→M+Q*. (D) Deactivation returns M* to the ground state by colliding with other molecules and releasing energy in the form of heat: M* → M + heat. (E) Emission returns M* to the ground state by emitting a photon: M* → M + hv.