42. Which of the following reagents should be used to convert hex-3-yne to (Z)-hex-3-ene       
(A) H₂, Pt
(B) Na, NH₃
(C) H₂, Lindlar's catalyst
(D) H₂SO₄, H₂O

38. Which of the following statements applies to the E2 mechanism? (A) It occurs with inversion of stereochemistry. (B) It occurs with racemization of stereochemistry. (C) It proceeds through the more stable carbocation intermediate. (D) The C-H and C-X bonds that break must be anti.

39. What is the major product of the following reaction? (A) (B) (C) (D)

40. Provide the reagents necessary to complete the following transformation. (A) 1. BH3∙THF 2. H2O2, HO- (B) H2O, H2SO4 (C) OsO4, H2O2 (D) CH3CO3H

41. Which of the following reagents will convert 1 mole of 3-methylpent-1-yne into 3-methylpentane? (A) 1 mole of Br2 in CCl4 (B) 2 moles of Cl2 in CCl4 (C) 2 moles of HCl (D) 2 moles H2, Ni and heat

43. Which of the following statements correctly pertains to a pair of enantiomers? (A) They rotate the plane of polarized light by exactly the same amount and in opposite directions. (B) They rotate the plane of polarized light by differing amounts and in opposite directions. (C) They rotate the plane of polarized light by differing amounts and in the same direction. (D) The have different melting points.

44. Predict the specific rotation of the compound shown. (A) It is impossible to predict； it must be determined experimentally. (B) Because both asymmetric centers are R, the compound is dextrorotatory. (C) Because both asymmetric centers are S, the compound is levorotatory. (D) Zero； the compound is achiral.

45. What is the major difference between an antiaromatic and aromatic compound? (A) Only aromatic compounds follow Huckle's rule. (B) Antiaromatic compounds have at least one sp3 hybridized atom in the ring. (C) Antiaromatic compounds can assume a chair-like structure while aromatic compounds are nearly flat. (D) Aromatic compounds cannot have a charged atom in the structure.

46. Which of the following is an incorrect statement about the bromination of benzene by Br2 and FeBr3? (A) FeBr3 functions to increase the electrophilicity of Br2. (B) Formation of the sigma complex is the rate-determining step of the mechanism. (C) The carbanionic intermediate is resonance stabilized. (D) There is one carbon-containing intermediates in the mechanism.

47. Which of the following species is attacked by benzene in the electrophilic nitration reaction? (A) HNO3 (B) (C) NO2 (D)

48. Which of the following compounds will not undergo Friedel-Crafts acylation when treated with CH3CH2COCI,AICI3?(A) toluene (B) p-xylene (C) benzophenone (D) ethoxybenzene