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

62. What is the product of the following reaction? (A)(B)(C)(D)(E)

63. Stray light is a problem for spectrophotometers that are not tightly sealed. What is the main impact of stray light on the recorded absorbance? (A) The apparent absorbance is greater than the true absorbance and increases as the amount of stray light increases. (B) The apparent absorbance is greater than the true absorbance and decreases as the amount of stray light increases. (C) The apparent absorbance is less than the true absorbance and increases as the amount of stray light decreases. (D) The apparent absorbance is less than the true absorbance and decreases as the amount of stray light decreases. (E) It is impossible to determine effect of stray light on measured absorbance.

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

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

68. Which of the shown molecules fits the fragmentation pattern of the mass spectrum below the best? (A)(B)(C)(D)(E)

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