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

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–

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

79. HNO2(l) + NaCl(s) → HCl(g) + NaNO2(s) Calculate the ΔH° value for the reaction above based on the information below. (A) –78.5 kJ (B) –157 kJ (C) 0 kJ (D) 78.5 kJ (E) 157 kJ

80. The crystal field diagram for a linear transition metal complex ML2 where the ligands lie along the z axis is shown below. Which of the following statements is correct? (A) A orbital is dx 2 -y 2 (B) B orbital and C orbital are dxz and dyz (C) A orbital is dxy (D) B orbital and C orbital are dx 2 -y 2 and dz 2 (E) A orbital is dz 2

81. Consider the following complexes: (en=H2N–CH2–CH2–NH2 and is bidentate)Which can exhibit cis-trans isomerism? (A) I (B) I and II (C) I, II, and III (D) I, II, III, and IV (E) I, II, and IV

82. Four solutions have violet, blue, yellow and green color, respectively. Each solution contains the following compounds: I. [Cr(H2O)4Cl2]Cl, II. [Cr(H2O)5Cl]Cl2, III. [Cr(H2O)6]Cl3, IV. [Cr(ethylenediamine)3]Cl3. Please use the following table to predict the color for each solution. (A) I: green; II: blue; III: violet; IV: yellow (B) I: yellow; II: violet; III: blue; IV: green (C) I: green; II: yellow; III: violet; IV: blue (D) I: green; II: violet; III: blue; IV: yellow (E) I: violet; II: blue; III: green; IV: yellow

83. Which of the following statements is the best to describe the results of attempted separation by fractional distillation of the two isomers of 1,2-dichloroethene? (A) They can be separated by fractional distillation, with isomer 1 boiling at the lower temperature. (B) They can be separated by fractional distillation, with isomer 2 boiling at the lower temperature. (C) They cannot be separated by fractional distillation because both isomers have the same boiling point. (D) They cannot be separated by fractional distillation because they interconvert rapidly at the distillation temperature. (E) They cannot be separated by fractional distillation because they have the same molecular weight and reactivity.