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

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.

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.

88. A galvanic cell consists of two half-reactions:What is the maximum work can be obtained from this cell at standard condition? (Faraday constant = 96500 C mol‒1 ) (A) 173.7 kJ (B) 347.4 kJ (C) 569.4 kJ (D) 113.9 kJ (E) None of the above.

89. Alkali metals (Group 1) are different with alkaline earth metals (Group 2). Which of the following statements is correct? (A) Alkali metals have larger ionic radii. (B) Alkali metals have higher melting points. (C) Alkali metals have greater first ionization energies. (D) Alkali metals have greater densities. (E) Alkali metals have greater electronegativity.

90. The partial pressure of CO2(g) is 0.22 atm and that of CO(g) is 0.44 atm in a mixture of the two gases at 25ºC. What is the mass fraction of CO2 in the mixture? (atomic weight: C = 12 g/mol, O = 16 g/mol) (A) 44% (B) 56% (C) 33.3% (D) 66.7% (E) 50%