40.Which of the following is least able to serve as a nucleophile in a chemical reaction?
(A)Br^-
(B)OH^-
(C)NH₃
(D)CH₃⁺
(E)I^-

36.Which of the following atoms is paramagnetic? (A)Cd (B)Tl1- (C)Nb1+ (D)Ni (E)Ru1+

複選題37.Which of the following statements is not true? (A)trans-1,3-dimethylcyclohexane is more stable than cis –1,3-dimethylcyclohexane. (B)trans-1,2-dimethylcyclohexane is more stable than cis–1,2-dimethylcyclohexane. (C)trans-1,4-dimethylcyclohexane is more stable than cis–1,4-dimethylcyclohexane. (D)trans-1,2-dimethylcyclohexane is more stable than cis–1,3-dimethylcyclohexane. (E)trans-1,2-dimethylcyclohexane is less stable than cis–1,3-dimethylcyclohexane. 

38.The approximate pKa of NH3 is 36; that of C2H5OH is 16. From this information, which (if any) of the following conclusion is (or are) correct? (A)The conjugate base of C2H5OH is stronger. (B)The conjugate base of NH3 is stronger. (C)C2H5OH is a weaker acid than NH3 (D)None of the these is correct. (E)All of these are correct.

39.The activation energy(Eact) of a give reaction is unrelated to which of the following parameters? (A)The rate of the slowest step of a multistep reaction. (B)The rate of the overall teaction. (C)The heat absorbed or given off by the reaction (DH) (D)The stability of the transition state. (E)None of these.

41.Thiols are alcohol analogs in which the oxygen has been replaced by sulfur (e.g., CH3SH). Given the fact that the S-H bond is less polar than the O-H bond, which of the following statements comparing thiols and alcohols is correct? (A)Hydrogen bonding forces are weaker in thiols. (B)Hydrogen bonding forces are stronger in thiols (C)Hydrogen bonding forces would be the same. (D)No comparison can be made without additional information. (E)None of these.

42.Rank the transition states which occur during the following reaction steps in order of increasing stability (least→most stable): (a)CH3 - OH2+→CH3 + +H2O (b)(CH3)3C - OH2+→(CH3)3C + + H2O (c)(CH3)2CH - OH2+→(CH3)2CH+ + H2O (A)a < b < c (B)b < c < a (C)a < c < b (D)b < a < c (E)c < b < a

43.An alkane with a molecular formula C6H14 reacts with chlorine in the presence of light and heat. Four constitutionally isomeric monochlorides of molecular formula C6H13Cl are formed (along with a mixture of dichlorides, trichlorides, and so on). What is the most reasonable structure for the starting alkane? (A)CH3CH2CH2CH2CH2CH3 (B)(CH3)2CHCH2CH2CH3 (C)CH3CH(CH2CH3)2 (D)(CH3)3CCH2CH3 (E)(CH3)2CHCH(CH3)2

44.Carboxylic acids exist in the vapor state as: (A)Monomeric species (B)Cyclic esters (C)Cyclic dimers (D)Cyclic trimers (E)None of these

45.The product from the reaction of 1-pentene with Cl2 in H2O is named: (A)1-Chloro-2-pentanol (B)2-Chloro-2-pentanol (C)1-Chloro-1-pentanol (D)2-Chloro-1-pentanol (E)none of these

46.In the traction of a reagent such as HBr with an alkene, the frist step of the reaction is the to ______the alkene.(A)Fast addition of an electrophile(B)Fast addition of a nuclephile(C)Slow addition of an electrophile(D)Slow addition of a nuclephile(E)none of these