24. Which of the following is correct in order of decreasing nucleophilicity toward methyl iodide in methanol?
(A) CH₃O^- > CH₃S^- > CN^- > Br^-
(B) CH₃O^- > CN^- > CH₃S^- > Br^-
(C) CN^- > CH₃O^- > CH₃S^- > Br^-
(D) CH₃S^- > Br^- > CH₃O^- > CN^-
(E) CH₃S^- > CN^- > CH₃O^- > Br^-

20. Energy is __________ when bonds are formed and is __________ when bonds are broken; therefore, bond dissociation energies are always __________. (A) released / consumed / exothermic (B) released / consumed / endothermic (C) consumed / released / exothermic (D) consumed / released / endothermic (E) consumed / released / isothermic

21. Which of the following are correct Lewis structures, including formal charges, for nitric acid, HNO3?  (A) A only (B) B only (C) C only (D) both B and C (E) A, B, and C

22. Which of the following alkyl chlorides is least likely to undergo rearrangement during a solvolysis reaction? (A) cis-1-chloro-2-ethylcyclohexane (B) trans-1-chloro-2-ethylcyclohexane (C) 2-chloro-4-methylpentane (D) 2-chloro-3-methylpentane (E) 2-chloro-2-methylpentane

23. Which of the following descriptions of the nucleoside uridine does not apply to the structure of the molecule? (A) The uracil base is directly bonded to the 1' position of ribofuranose in the α position. (B) The ribofuranose moiety is found in only the D configuration. (C) Nitrogen, at position 1 in the uracil base, is directly bonded to the ribofuranose moiety. (D) The 5' OH group is replaced with phosphate(s) in the nucleotide structure. (E) none of the above

25. Which of the following compounds will undergo SN2 reaction most readily? (A) (CH3)3CCH2I (B) (CH3)3CCl (C) (CH3)2CHI (D) (CH3)2CHCH2CH2CH2I (E) (CH3)2CHCH2CH2CH2Cl

26. Which of the following carbonyl compounds can be reduced by H2/Raney Ni? (A) acetic acid (B) ethyl acetate (C) acetyl chloride (D) acetamide (E) N-methyl acetamide

27. Which of the following is the rate-determining step for the monobromination of cyclohexane? (A) Step I (B) Step II (C) Step III (D) Step IV (E) Step V

28. What is the major organic product of the following reaction? 

29. Which are ylides?  (A) only I (B) only II (C) I and II (D) II and III (E) III and IV

30. Which of the following chemical reactions could be used to distinguish between a polyunsaturated vegetable oil and a petroleum oil containing a mixture of saturated and unsaturated hydrocarbons? (A) addition of bromine in carbon tetrachloride (B) ozonolysis (C) hydrogenation (D) lipidification (E) saponification