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

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

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

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.

84. Which isomers of C4H8 has the lowest absolute entropy at 25°C? (A) 1-butene (B) cis-2-butene (C) trans-2-butene (D) 2-methylpropene (E) cyclobutane

85. What are the factors influencing the infrared frequency of the CX vibration for CH3X? I. mass of X II. strength of the CX bond III. type of CX vibration (stretch or bend) (A) I (B) II (C) I and II (D) II and III (E) I, II, and III

86. The radioactive isotope 247Bk (Z = 97) decays by a series of α-particle and β-particle productions, taking 247Bk through many transformations to end up as 207Pb (Z = 82). In the complete decay series, how many α particles and β particles are produced, respectively? (A) 10, 8 (B) 10, 5 (C) 10, 2 (D) 8, 8 (E) 5, 8

87. Consider the galvanic cell shown below (the contents of each half-cell are written beneath each compartment). The standard reduction potentials are as follows: Which of the following statements about this cell is incorrect? (A) The value of E° for this cell is 1.82 V (B) Electrons flow from the Cr electrode to the Pt electrode. (C) Reduction occurs at the Cr electrode. (D) The cell is not at standard conditions. (E) The value of E for this cell at 25°C should larger than 1.82 V.