72. In the blood of an adult human, there are approximately 2.64 ✖ 10¹³ red blood cells with a total of 2.90 g of iron. On the average, how many iron atoms in each red blood cell? (Fe = 55.85 g/mol)
(A) 5.19 ✖  10^–2
(B) 4.72 ✖ 10¹¹
(C) 1.09 ✖  10^–13
(D) 9.10 ✖  10¹²
(E) 1.18 ✖  10⁹

複選題68. NF3 has a bond angle of 102.5º, while PF3 has a bond angle of 96.3º. What is the best explanation for the larger bond angle in NF3? (A) The nitrogen 2s orbital participates more in bonding than the phosphorus 3s orbital does. (B) Nitrogen is more electronegative than phosphorus. (C) NF3 has no unpaired electrons while PF3 has two unpaired electrons. (D) NF3 is an ionic compound while PF3 forms covalent bonds. (E) NF3 adopts a trigonal geometry, while PF3 displays a trigonal planar configuration.

69. When the reaction below is at equilibrium, what is the temperature? 2 NO(g) + O2(g) → 2 NO2(g) H   rxn = –113 kJ•mol–1 S°rxn = –145 J•mol–1 •K–1 (A) –195 °C (B) 77.9 °C (C) 350.9 °C (D) 506 °C (E) 779 °C

70. Please balance the following equation (o, p, q, x, y, z are reaction coefficients). What is the sum of all coefficients (o + p + q + x + y + z) ? (A) 18 (B) 20 (C) 22 (D) 24 (E) 26

71. For the reaction A + B  products, the following data were obtained: What is the experimental rate law? (A) Rate = k[A] (B) Rate = k[B] (C) Rate = k[A][B] (D) Rate = k[A]2 [B] (E) Rate = k[A][B]2 

73. What is the rate constant for radioactive decay of 14CO2(g) at 0.1 atm? (The half-life of C-14 nucleus is 5730 years.) (A) 1.38 × 10‒8 h ‒1 (B) 2.76 × 10‒8 h ‒1 (C) 1.38 × 10‒9 h ‒1 (D) 3.45 × 10‒9 h ‒1 (E) 6.90 × 10‒9 h ‒1

74. 1 mg of a non-electrolyte protein is dissolved in enough water to make 1.00 mL of solution. The osmotic pressure of the solution is found to be 1.56 torr at 25ºC. The molecular weight of this protein is approximately ________ g. (A) 1.19 × 107 (B) 11905 (C) 5950 (D) 999 (E) None of the above

75. When the permanganate ion, MnO4ˉ, acts as an oxidizing agent which forms different products depending on the pH of the solution. Which species corresponding to the conditions listed below is correct? (A) A (B) B (C) C (D) D (E) E

76. Alanine, H2NCH(CH3)CO2H, has Ka = 4.5 × 10–3 and Kb = 7.4 × 10–5 . Which species has the highest concentration in water (pH=7.0)? (A) H2NCH(CH3)CO2H (B) +H3NCH(CH3)CO2H (C) H2NCH(CH3)CO2 – (D) H2NCH(CH3)CO2H2 + (E) +H3NCH(CH3)CO2 –

77. The rate of effusion of an unknown gas is measured and found to be 24 mL/min. Under the same condition, the rate of effusion of CO gas is 38 mL/min. Which is the best formula of this unknown gas? (A) CO2 (B) H2O (C) C5H10 (D) C6H6 (E) C2H5OH

78. An unknown concentration of NH3 solution is titrated by HCl solution. The color change for indicators at different pH values are shown in the table below. Which of the following indicators is the best for this titration? (A) phenolphthalein (B) alizarine yellow R (C) methyl red (D) crystal violet (E) thymol blue