64. The iron in a 0.6656-g ore sample was reduced quantitatively to the +2 state and then titrated with 26.75 mL of the KMnO₄ solution (0.02966 M). Calculate the percentage of Fe₂O₃ (Fe=55.8 g/mol) in the sample.
(A) 95.12 %
(B) 47.56 %
(C) 43.12 %
(D) 38.04 %
(E) 19.02 %

60. Rank the following molecules in order of decreasing C-C bond length of their shortest C-C bonds. ① benzene ② 1,3-butadiene (CH2CHCHCH2) ③ 1,2-propadiene (CH2CCH2) ④ethyne (HCCH) (A) ① ＞ ②＞ ③ ＞④ (B) ④＞ ③＞ ②＞ ①(C) ③＞ ②＞ ④ ＞ ① (D) ①＞ ③＞ ② ＞ ④ (E) ④＞ ② ＞ ③＞ ① 

II. Choose one correct answer for the following questions61. Which one is CORRECT for buffer capacity of a solution? (A) It is defined as the number of moles of a strong acid or a strong base that cause 1 mL of the buffer to undergo a 1.00-unit change in pH. (B) It depends only on the total concentration of buffers, not on their concentration ratio. (C) The pKa of the acid chosen for a given application should lie within ± 1 unit of the desired pH for the buffer. (D) A buffer solution of any desired pH can be prepared by combining calculated quantities of buffer pair, no need any adjustment. (E) Dissociation constants would not interfere with the predicted pH values.

62. There is a titration of 50.00 mL of 0.0500 M Fe2+ with 0.1000 M Ce4+ in a medium (1.0 M H2SO4). Calculate the potential after the addition of 25.00 mL of Ce4+. Ce4+ + e- → Ce3+      Eo = 1.44 V (1 M H2SO4) Fe3+ + e- → Fe2+       Eo = 0.68 V (1 M H2SO4) (A) 0.64 V (B) 1.06 V (C) 1.56 V (D) 2.01 V (E) 2.21 V

63. What mass of Ba(IO3)2 (487 g/mol) (Ksp = 1.57 × 10-9) can be dissolved in 400.0 mL of water at 25℃? (A) 0.732 mg (B) 5.45 mg (C) 0.142 g (D) 0.178 g (E) 0.280 g

65. Which of the following compounds does NOT react with acetyl chloride? (A) C2H5OH (B) C6H6 + AlCl3 (C) CH3COONa (D) C2H5Cl (E) C2H5NHC2H4OH

66. A compound exhibits an infrared band at 2245 cm-1 and is hydrolysed by mineral acid to give an organic acid. The original compound is: (A) an ester (B) an amide (C) a nitrile (D) an acid anhydride (E) an alkyne

67. Compound X has an empirical formula CH2 and a molecular weight of 84. When X is subjected to ozonolysis two organic products are obtained; only one of these reduces Fehling's solution and both give positive iodoform reactions. X is: (A) hex-1-ene (B) hex-2-ene (C) hexa-1,4-diene (D) 3-methylpent-2-ene (E) 2,3-dimethylbut-2-ene

68. Metathesis reactions have been known for many years, and one of examples is given as follow.What catalyst is commonly used in running the metathesis reactions? (A) Lindlar catalyst (B) Raney nickel (C) Grubbs’ catalyst (D) Pd(OH)2/C (E) None of above

69.If the above reaction was strictly SN1, the organic product(s) would be: (A) ① only (B) ① and ② (C) ①, ② and ③ (D) ② only (E) ③ only

70. The minimum concentration of oxygen necessary to sustain fish life in an aquarium is 4 mg/L. Assuming the density of the aquarium water solution is 1.00 g/mL, what is the minimum concentration of O2 expressed in parts per million (ppm). (A) 2 ppm (B) 4 ppm (C) 2000 ppm (D) 250 ppm (E) 0.004 ppm