66. The half-life of ¹⁴C is 5730 years. A sample taken for radiocarbon dating has been found to contain56 % of its original ¹⁴C. Which of the following options is the best estimate for the age of the sample? (Radioactive decay of ¹⁴C follows first-order kinetics.)
(A)4.8x10²
(B) 4.8x10³
(C) 4.8x 10⁵
(D) 4.8 x 10⁶
(E) 4.8 x 100

62. What is the role of AlCl3 in the reaction of benzene and Cl2? (A) To act as a nucleophile (B) To act as an electrophile (C) To strengthen the Cl–CI bond (D) To increase the reactivity of the electrophile (E) To act as a neutral species

63. Which of the following methods can be used to determine the molecular weight of a protein?Ⅰ: Sodium dodecyI sulfate-polyacrylamide gel electrophoresis； Ⅱ: Size-exclusion chromatography； Ⅲ: Electrospray ionization mass spectrometry； IV: Infrared spectroscopy； V: Ultraviolet-visible spectroscopy (A) Ⅰ, Ⅱ, Ⅲ, IV,V (B) Ⅰ,Ⅱ, Ⅲ, IV (C)  Ⅰ, Ⅱ, Ⅲ (D) Ⅰ, Ⅱ (E) Ⅰ

64. Boron consists of two isotopes, 10B and 11B. Chlorine also has two isotopes, 35CI and 37CI. Consider the mass spectrum of BCl3. How many peaks would be present? (A)7 (B)8 (C)9 (D) 10 (E) 11 

65. Which of the following statements about I D NMR and 2D NMR spectroscopy is INCORRECT? (A) ID NMR is faster than 2D NMR. (B) ID NMR gives less information than 2D NMR. (C) 2D NMR spectrum provides information about the spatial relationships between different nuclei in the sample, such as the distances and angles between atoms. (D) 2D NMR distinguishes between the overlapping signals that exist in larger molecules. (E) The advantage of 2D NMR spectroscopy is that it requires only one frequency axis.

67. Sort the molecules in the order from the largest bond angle to the smallest bond angle: H2O, NH3, BF3, CH4, CO2 (A) CH4, CO2, H2O, BF3, NH3 (B) CO2, BF3, CH4, NH3,H2O (C) NH3, H2O, BF3, CO2, CH4 (D) H2O, NH3, BF3, CH4, CO2 (E) BF3, NH3,  H2O, CH4, CO2

68. If the ionization energy of a hydrogen atom is 13.6 eV, the energy required to excite it from ground state to the next higher state is approximately: (A) 3.4eV(B)10.2eV(C)17.2eV(D)13.6eV(E)6.8 ev

69. Hemocyanins (Hc) are proteins that transport oxygen throughout the bodies of some invertebrate animals. These metalloproteins contain two copper atoms that reversibly bind a single oxygen molecule (O2). The scheme below shows a proposed structure of how the copper atoms bind to oxygen. What is the oxidation state of the copper atoms in the product? L is a neutral ligand.   (A)+1,+1(B)+2,+2(C)+3,+3(D)+0.5.0.5(E)+1.5.+1.5

70. The value of the Bohr radius for hydrogen is: (A)0.529 x 10-6cm (B) 0.529 x 10-8cm (C) 0.529 x 10-10cm (D) 0.529 x 10-12 cm (E) 0.529 x 10-14 cm 

71 . Select the rate law that corresponds to the data shown for the following reaction: A+B→ Products [X]0 represents the initial concentration for a species X.(A) Rate = k[A]3 (B) Rate = k[A]2[B]1 (C) Rate = k[A]1[B]2 (D) Rate = k[B]3 (E) None of the above

72. Which one of the following tetrahedral MXF- complexes has the strongest crystal field stabilization? (A) FeCl42- (B) MnCl42- (C) CoCl42- (D) NiCI42- (E) CuCI42-