43. The alpha helix of a protein is held in a coiled conformation partly because of
(A) hydrogen bonding
(B) optical activity
(C) active sites
(D) double bonding
(E) none

39. Which of the following statements about the complex ion is true? (A) the complex ion contains Co(I) (B) The complex ion exhibits cis and trans geometric isomers, but no optical isomers (C) the complex ion exhibits two geometric isomers (cis and trans) and two optical isomers (D) because en is a strong field ligand, the complex ion is paramagnetic (E) the geometric isomers of the complex ion have identical chemical properties

40. Which of the following is not a structural isomer of 1-pentene? (A) 2-pentene (B) 2-methyl-2-butene (C) cyclopentane (D) 3-methyl-1-butene (E) 1-methyl- cyclobutene

41. Consider the molecule trans-2-butene. Which statement is true? (A) the molecule has two π bonds (B) there is free rotation around every bond in the molecule (C) cis-2-butene is its structural isomer (D) carbon #2 exhibits sp² hybridization (E) none of these

42. Aspirin is formed via a(n) _ reaction. (A) combustion (B) hydrogenation (C) addition (D) condensation (E) substitution

44. The isotactic, syndiotactic, and atactic forms of polypropylene differ in (A) the functional groups they contain around the carbon backbone (B) the terminating functional groups they contain (C) the positions of the methyl groups around the carbon backbone (D) the number of methyl groups around the carbon backbone (E) both C and D

45. Choose the correct molecular structure for XeF6. (A) trigonal bipyramidal (B) trigonal planar (C) tetrahedral (D) octahedral (E) none of these

46. Phosphorus is found in nature as (A) white phosphorus (B) red phosphorus (C) black phosphorus (D) usually as the ion in phosphate rock (E) in gypsum

47. Compounds containing bismuth in the +5 oxidation state tend to be _ and compounds containing bismuth in the +3 oxidation state tend to be _ (A) ionic, ionic (B) ionic, molecular (C) molecular, molecular (D) molecular, ionic (E) none of these

48. Which of the following elements exhibit(s) the oxidation states +1 and +3? (A) B (B) Al (C) Ga (D) T1 (E) none of these

49. Choose the metal that reacts least vigorously with water. (A) Mg (B) Ca (C) Sr (D) Ba (E) all of these react equally vigorously with water