41. Indicate the alcohols (or acids) has the lowest pKa value?
(A) 2,2,2-trifluoroethanol
(B) 2,2-dimethylpropanol
(C) 2,2,2-trichloroethanol
(D) cyclopropanol
(E) cyclohexanol

37. Which of the following will not produce a buffered solution? (A) 100mLof0.1MNa2C03and50mLof0.1 MHC1 (B) 100 mL of 0.1 MNaHCO3, and 25 mL of 0.2M HC1 (C) 100 mL of 0.1 M Na2CO3, and 75 mL of 0.2 M HC1 (D) 50 mL of 0.2 M Na2CO3 and 5 mL of 1.0 M HC1 (E) lOOmLofO.l MNa2C03 and50mLof0.1 MNaOH

38. In the titration of a weak acid HA with 0.100 M NaOH the stoichiometric point is known to occur at a pH value of approximately 10. Which of the following indicator acids would be best to use to mark the endpoint of this titration? (A) indicator A, 10-14 (B) indicator B,iTa= 10-11  (C) indicator C,Ka= 10-8 (D) indicator D, Ka = 10-6 (E) none of these

39. Silver acetate (AgC2H3O2)is a sparingly soluble salt with Ksp = 1.9 ✖ 10- 3. Consider a saturated solution in equilibrium with the solid salt. Compare the effects on the solubility of adding to the solution either the acid HNO3, or the base NH3. (A) Either substance would decrease the solubility. (B) NH3 would increase the solubility, but HNO3, would decrease it. (C) NH3 would increase the solubility, but HN03 would have virtually no effect. (D) Either substance would increase the solubility. (E) NH3 would decrease the solubility, but HN03 would increase it. .

40. Which of the following compounds is an achiral compound?(A)(B)(C)(D)(E)

42. Consider the NMR spectrum of BA, which is shown below. The formula of compound BA is C8H7C1O.The structure of BA is (A)(B)(C)(D)(E) None of the above .

43. When compound I was heated in ethanol, an ether product was collected (shown below)The mechanism of this reaction is (A) SN2 (B) E2 (C) SN1 (D) El (E) none of above

44. To complete the following reaction, please choose the best reaction condition? (A) B2H6then H2O2/Na0H (B) HC1 (C)OsO4 then H2O2(D) O3 then Me-S-Me (E) Hg(OAc)2 then NaBH4

45. The composition of compound AZ is C7H140 and its spectrum shows the following signals: 6H triplet at 0.9 5, Hz; 4H cextet at 1.6 5. J=1 Hz: 4H triplet at 2.4 5, J=1 Hz. What is the structure of compound AZ?(A)(B)(C)(D)(E) None of the above

46. The rate of a reaction typically increases as the temperature increases because. (A) the A term in the Arrhenius equation increases. ' (B) the fraction of molecules with kinetic energy greater than Ea increases. (C) the activation energy decreases. (D) the activation energy increases. (E) the molecules make more collisions with the wall of the reaction vessel.

47. If a mixture contains 75% of one compound and 25% of its enantiomer，what is the e.e. of the mixture? (A) 100 (B) 75 (C) 50 (D) 25 (E) 3