81. Which of the following cycloalkenes would be expected to be stable?

(A) f and ff
(B) ff and fff
(C) ff
(D) f and fff
(E) All are stable.

77. Three electrochemical cells were connected in series so that the same quantity of electrical current passes through all three cells. fn the first cell, 1.15 g of chromium metal was deposited from a chromium(III) nitrate (Cr(NO3)3) solution. fn the second cell, 6.31 g of osmium was deposited from a solution made of Osn+ and nitrate ions.Choose the correct name of the salt. Cr=52.0 g/mol; Os=192.2 g/mol(A) osmium(II) nitrate (B) osmium(III) nitrate (C) osmium(IV) nitrate(D) osmium(V) nitrate (E) osmium(VI) nitrate

78. A pain relief medication indicates that every 6 g of powder contains approximately 480 mg of ibuprofen. Assuming all of the active ingredients are ibuprofen, the powder is fully dissolved in 0.5 L of isopropanol. What is the approximate concentration of ibuprofen in the resulting solution in ppm? (The density of isopropanol is 0.79 g/cm3.)(A) 0.12 ppm (B) 480 ppm (C) 960 ppm (D) 1215 ppm (E) 1304 ppm

79. Consider the molecular orbital energy level diagrams for O2 and NO. Which of the following statement is correct?I. Both molecules are paramagnetic.II. The bond strength of O2 is greater than the bond strength of NO.III. NO is an example of a heteronuclear diatomic molecule.IV. The ionization energy of NO is smaller than the ionization energy of NO+.(A) I only (B) I and II (C) I and III (D) II and III (E) I, III, and IV

80. Peramivir has shown to be effective against the influenza B virus.What is the degree of unsaturation in Peramivir?(A) 2 (B) 3 (C) 4 (D) 5 (E) 6

82. What is the structural relationship of the following two compounds?(A) same compound (B) enantiomers (C) cis-trans isomers(D) structural isomers (E) diastereomers

83. Two complex ions containing Ni are , which is blue, and , which is purple.Which one of these statements is correct? (en = H2N–CH2–CH2–NH2)(A) The wavelength of the light absorbed by is greater than the wavelength absorbedby .(B) The energy of the photon absorbed by [Ni(en)3]2+ is greater than that absorbed by.(C) Both complex ions are diamagnetic.(D) absorbs light in the violet region of the spectrum.(E) The crystal field splitting energy () is greater for than for .

84. Which of the following becomes more soluble in water upon addition of NaOH?(A) an amine (B) a carboxylic acid (C) a phenol(D) an alkane (E) two of these

85. Given the compound as shown below: Which of the labeled H atoms (1-5) in the following molecule would be predicted to be the most acidic?(A) 1 (B) 2(C) 3(D) 4(E) 5

86. Which of the following compounds exhibits the highest stability?(A) 2-methyl-1,2-pentadiene (B) (Z)-2-methyl-1,3-pentadiene(C) （E）-2-methyl-1,3-pentadiene (D) 2-methyl-2,3-pentadiene(E) 2-methyl-1,4-pentadiene

87. A metal fluoride crystallizes in a close-packed arrangement of fluoride ions, with the metal ions occupying one-half of the octahedral holes. What is the formula of this compound?(A) MF (B) MF2 (C) MF3 (D) M2F (E) M2F3