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2014美国奥林匹亚化学试题


2014 U.S. NATIONAL CHEMISTRY OLYMPIAD
LOCAL SECTION EXAM
Prepared by the American Chemical Society Chemistry Olympiad Examinations Task Force

OLYMPIAD EXAMINATIONS TASK FORCE
Arden P. Zipp, Chair, State University of New York, Cortland, NY (deceased)
James Ayers, Mesa State College, Grand Junction, CO Mark DeCamp, University of Michigan, Dearborn, MI Marian DeWane, Centennial High School, Boise, ID Xu Duan, Holton-Arms School, Bethesda, MD Valerie Ferguson, Moore High School, Moore, OK Julie Furstenau, Thomas B. Doherty High School, Colorado Springs, CO Kimberly Gardner, United States Air Force Academy, CO Paul Groves, South Pasadena High School, South Pasadena, CA Preston Hayes, Glenbrook South High School, Glenbrook, IL (retired) Adele Mouakad, St. John's School, San Juan, PR (retired) Jane Nagurney, Scranton Preparatory School, Scranton, PA Ronald Ragsdale, University of Utah, Salt Lake City, UT
DIRECTIONS TO THE EXAMINER This test is designed to be taken with an answer sheet on which the student records his or her responses. All answers are to be marked on that sheet, not written in the booklet. Each student should be provided with an answer sheet and scratch paper, both of which must be turned in with the test booklet at the end of the examination. Local Sections may use an answer sheet of their own choice. The full examination consists of 60 multiple-choice questions representing a fairly wide range of difficulty. Students should be permitted to use non-programmable calculators. A periodic table and other useful information are provided on page two of this exam booklet for student reference. Suggested Time: 60 questions—110 minutes DIRECTIONS TO THE EXAMINEE DO NOT TURN THE PAGE UNTIL DIRECTED TO DO SO. This is a multiple-choice examination with four choices for each question. There is only one correct or best answer to each question. When you select your choice, blacken the corresponding space on the answer sheet with your pencil. Make a heavy full mark, but no stray marks. If you decide to change your answer, be certain to erase your original answer completely.

Property of ACS USNCO – Not for use as USNCO Local Section Exam after March 31, 2014 Distributed by the American Chemical Society, 1155 16 th Street, N.W., Washington, DC 20036 All rights reserved. Printed in U.S.A.

amount of substance ampere atmosphere atomic mass unit Avogadro constant Celsius temperature centi– prefix coulomb density electromotive force energy of activation enthalpy entropy equilibrium constant

n A atm u NA °C c C d E Ea H S K

ABBREVIATIONS AND SYMBOLS Faraday constant F molar mass free energy G mole frequency ? Planck’s constant gas constant R pressure gram g rate constant hour h reaction quotient joule J second kelvin K speed of light kilo– prefix k temperature, K liter L time measure of pressure mm Hg vapor pressure milli– prefix m volt molal m volume molar M

CONSTANTS M mol h P k Q s c T t VP V V R = 8.314 J?mol 1?K
– – –1 –1

R = 0.0821 L?atm?mol 1?K 1 F = 96,500 C?mol
–1 –1

1 F = 96,500 J?V–1?mol NA = 6.022 ? 1023 mol h = 6.626 ? 10–34 J?s c = 2.998 ? 108 m?s 1 0 °C = 273.15 K 1 atm = 760 mm Hg


–1

EQUATIONS

E ? Eo ?

RT ln Q nF

? ??H ?? 1 ? ln K ? ? ?? ? ? constant ? R ?? T ?

?k ? E ? 1 1 ? ln ? 2 ? ? a ? ? ? ? k1 ? R ? T1 T2 ?

1 1A 1 H
1.008

PERIODIC TABLE OF THE ELEMENTS
2 2A 4 Be
9.012

3 Li
6.941

13 3A 5 B
10.81

14 4A 6 C
12.01

15 5A 7 N
14.01

16 6A 8 O
16.00

17 7A 9 F
19.00

18 8A 2 He
4.003

10 Ne
20.18

11 Na
22.99

12 Mg
24.31

19 K
39.10

20 Ca
40.08

3 3B 21 Sc
44.96

4 4B 22 Ti
47.88

5 5B 23 V
50.94

6 6B 24 Cr
52.00

7 7B 25 Mn
54.94

8 8B 26 Fe
55.85

9 8B 27 Co
58.93

10 8B 28 Ni
58.69

11 1B 29 Cu
63.55

12 2B 30 Zn
65.39

13 Al
26.98

14 Si
28.09

15 P
30.97

16 S
32.07

17 Cl
35.45

18 Ar
39.95

31 Ga
69.72

32 Ge
72.61

33 As
74.92

34 Se
78.96

35 Br
79.90

36 Kr
83.80

37 Rb
85.47

38 Sr
87.62

39 Y
88.91

40 Zr
91.22

41 Nb
92.91

42 Mo
95.94

43 Tc
(98)

44 Ru
101.1

45 Rh
102.9

46 Pd
106.4

47 Ag
107.9

48 Cd
112.4

49 In
114.8

50 Sn
118.7

51 Sb
121.8

52 Te
127.6

53 I
126.9

54 Xe
131.3

55 Cs
132.9

56 Ba
137.3

57 La
138.9

72 Hf
178.5

73 Ta
180.9

74 W
183.8

75 Re
186.2

76 Os
190.2

77 Ir
192.2

78 Pt
195.1

79 Au
197.0

80 Hg
200.6

81 Tl
204.4

82 Pb
207.2

83 Bi
209.0

84 Po
(209)

85 At
(210)

86 Rn
(222)

87 Fr
(223)

88 Ra
(226)

89 Ac
(227)

104 Rf
(261)

105 Db
(262)

106 Sg
(263)

107 Bh
(262)

108 Hs
(265)

109 Mt
(266)

110 Ds
(281)

111 Rg
(272)

112 Cn
(285)

113
(Uut) (284)

114
(Uuq) (289)

115
(Uup) (288)

116
(Uuh) (293)

117
(Uus) (294)

118
(Uuo) (294)

58 Ce
140.1

59 Pr
140.9

60 Nd
144.2

61 Pm
(145)

62 Sm
150.4

63 Eu
152.0

64 Gd
157.3

65 Tb
158.9

66 Dy
162.5

67 Ho
164.9

68 Er
167.3

69 Tm
168.9

70 Yb
173.0

71 Lu
175.0

90 Th
232.0

91 Pa
231.0

92 U
238.0

93 Np
(237)

94 Pu
(244)

95 Am
(243)

96 Cm
(247)

97 Bk
(247)

98 Cf
(251)

99 Es
(252)

100 Fm
(257)

101 Md
(258)

102 No
(259)

103 Lr
(262)

Page 2

Property of ACS USNCO – Not for use as USNCO Local Section Exam after March 31, 2014

DIRECTIONS ? ? ? When you have selected your answer to each question, blacken the corresponding space on the answer sheet using a soft, #2 pencil. Make a heavy, full mark, but no stray marks. If you decide to change an answer, erase the unwanted mark very carefully. There is only one correct answer to each question. Any questions for which more than one response has been blackened will not be counted. Your score is based solely on the number of questions you answer correctly. It is to your advantage to answer every question. 1. Which compound contains the highest percentage of magnesium by mass? (A) MgNH4PO4 (C) Mg2P4O7 2. (B) Mg(H2PO4)2 (D) Mg3(PO4)2 6. Which of the following is a weak electrolyte in aqueous solution? (A) HF (B) NaF (C) HCl (D) KCl

7. Which list gives nonmetals that are found in their elemental forms in nature? (A) neon, phosphorus, fluorine (B) helium, hydrogen, iodine (C) nitrogen, oxygen, sulfur (D) oxygen, chlorine, phosphorus

In the diagram above the paired open spheres represent H2 molecules and the paired solid spheres represent N2 molecules. When the molecules in the box react to form the maximum possible amount of ammonia (NH3) molecules, what is the limiting reactant and how many molecules of NH3 can be formed? (A) N2 is limiting. 5 molecules of NH3 can be formed. (B) N2 is limiting. 10 molecules of NH3 can be formed. (C) H2 is limiting. 8 molecules of NH3 can be formed. (D) H2 is limiting.12 molecules of NH3 can be formed. 3. Vanillin, C8H8O3 (M = 152 g/mol), is the molecule responsible for the vanilla flavor in food. How many oxygen atoms are present in a 45.0 mg sample of vanillin? (A) 1.78 × 1020 (C) 1.78 × 1023 (B) 5.35 × 1020 (D) 5.35 × 1023

8. Which one of the following cannot act as an oxidizing agent? (A) S2– (B) SO32– (C) SO42– (D) S2O82–

9. Which substance is the primary component in stalactites and stalagmites in caves? (A) CaO (B) CaCO3 (C) Ca(OH)2 (D) CaSO4

10. Five successive determinations of the density of an alloy gave the following results: 10.29 g/mL, 9.95 g/mL, 10.06 g/mL, 9.89 g/mL, 10.18 g/mL What value should be reported for the density of this alloy? (A) 10.074 g/mL (C) 10.1 + 0.2 g/mL (B) 10.07 + 0.16 g/mL (D) 1.0 × 101 g/mL

4. What is the molarity of sodium ions in a solution prepared by diluting 250. mL of 0.550 M Na2SO4 to 1.25 L? (A) 0.110 M (C) 0.220 M (B) 0.138 M (D) 0.275 M

11. A student is asked to analyze a water sample from a stream for total solids (TS), dissolved solids (DS), and suspended solids (SS). She carries out the experiments below. 1. A 25-mL portion of the water sample is evaporated to dryness in a pre-weighed evaporating dish to give mass 1. 2. A separate 25-mL portion is filtered into a second preweighed evaporating dish and evaporated to dryness to give mass 2. How are values for TS, SS and DS (per 25 mL water) determined? (A) TS = mass 1, SS = mass 1 – mass 2, DS = mass 2 (B) TS = mass 1, SS = mass 2, DS = mass 1 – mass 2 (C) TS = mass 1 + mass 2, SS = mass 1, DS = mass 2 (D) TS = mass 1 + mass 2, SS = mass 2, DS = mass 1

5. The solubility of K2Cr2O7 in water is 125 g/L at 20 °C. A solution is prepared at 20 °C that contains 6.0 grams of K2Cr2O7 in 50. mL of water. This solution is (A) dilute. (C) supersaturated. (B) saturated. (D) unsaturated.

Property of ACS USNCO – Not for use as USNCO Local Section Exam after March 31, 2014

Page 3

12. Which method(s) can be used to determine the concentration of HNO3 in an aqueous solution of nitric acid? I titration with a standard base II titration with a standard oxidizing agent III precipitation with Ag+ (A) I only (C) I and II only (B) III only (D) I, II, and III

18. The normal boiling point and vapor pressure at 25 °C are measured for liquids in two flasks. Flask A contains pure water and flask B contains a 1.0 M aqueous NaCl solution. Which flask contains the liquid with the higher boiling point? Which flask contains the liquid with the higher vapor pressure? Higher boiling point Higher vapor pressure (A) (B) (C) (D) Flask A Flask A Flask B Flask B Flask A Flask B Flask A Flask B

13. The kinetic theory of gases assumes all of the following EXCEPT: (A) Gases are composed of particles in random, ceaseless motion. (B) The sizes of gas particles are negligible compared to the size of the container. (C) Gas particles do not attract or repel each other. (D) When gas particles collide, kinetic energy is lost. 14. A sample of He gas in a flexible container at room temperature exhibits a certain pressure. What will be the new pressure when the absolute temperature and volume of the container are both halved? The pressure of the He will be (A) the same. (C) halved. (B) doubled. (D) quadrupled.

19. Given chemical equations for these reactions – S(s) + O2(g) ? SO2(g) ?H? –296.8 kJ?mol 1 – H2(g) + ? O2(g) ? H2O(l) ?H? –285.8 kJ?mol 1 –1 H2(g) + S(s) ? H2S(g) ?H? –20.6 kJ?mol What is the value of ?H for the reaction below? 2 H2S(g) + 3 O2(g) ? 2 H2O(l) + 2 SO2(g) (A) –603.2 kJ?mol–1 (C) –1206.4 kJ?mol–1 (B) –562.0 kJ?mol–1 (D) –1124.0 kJ?mol–1

20. Consider the following reactions I 2 NO2(g) ? N2(g) + 2 O2(g) II 2 IBr(g) ? I2(s) + Br2(l) For which reaction is ΔS° < 0? (A) I only (C) Both I and II (B) II only (D) Neither I nor II

15. The molecules in a sample of pure liquid dichloromethane, CH2Cl2, experience which of the following intermolecular forces? I dispersion forces II dipole-dipole forces III hydrogen bonding (A) I only (C) I and II only (B) II only (D) I, II, and III

21. Calculate the energy released by the reaction 4 Fe(s) + 3 O2(g) ? 2 Fe2O3(s) when a 55.8 g sample of iron reacts completely with 1.00 mole of oxygen. The enthalpy of formation (?Hf?) of – Fe2O3(s) is –826 kJ?mol 1. (A) 206 kJ (B) 413 kJ (C) 826 kJ (D) 1650 kJ

16. Which property best distinguishes metals from other types of solids? (A) Metals exhibit three-dimensional order. (B) Metals melt at low temperatures. (C) Metals have a shiny, silvery-white appearance. (D) Metals exhibit three-dimensional electrical conductivity. 17. What type of solid is silicon carbide, SiC? (A) ionic (C) molecular (B) metallic (D) network covalent

22. The specific heat capacities of three metals are given below. Metal Fe Pb Zn – – 0.470 0.130 0.388 Specific heat, J?g 1?°C 1 If 1.00 g of each metal is heated to 100 °C and added to 10.0 g of H2O at 25.0 °C, what is the order of the temperatures of the final mixtures from the lowest to the highest? (A) Fe < Zn < Pb (C) Zn < Pb < Fe (B) Pb < Zn < Fe (D) Zn < Fe < Pb

23. The enthalpy of formation, ?Hf?, equals zero at 25 °C for which of the following in their standard states? (A) elements (C) gases (B) compounds (D) solids

Page 4

Property of ACS USNCO – Not for use as USNCO Local Section Exam after March 31, 2014

24. Liquid water is injected into an oven at 400 K. What are the signs for ?G, ?H, and ?S for the physical transformation that occurs? (A) (B) (C) (D) (A) (A) ?G + + – – (B) (B) ?H – – + + (C) (C) ?S – 0 + 0 (D) (D)

29. A first-order reaction is carried out at several different temperatures. The data are plotted as ln k vs 1/T. How is the slope of the graph related to Ea? (A) Ea = slope × 8.314 J?mol–1?K–1 (B) Ea = –slope × 8.314 J?mol–1?K–1 (C) 1/Ea = slope × 8.314 J?mol–1?K–1 (D) 1/Ea = –slope × 8.314 J?mol–1?K–1 30. Which statement about the behavior of a catalyst is correct? (A) A catalyst reacts with the product and shifts the equilibrium to the right speeding up the reaction. (B) A catalyst lowers the activation energy of the original reaction pathway. (C) A catalyst provides additional energy to a reactant so it can achieve the necessary activation energy. (D) A catalyst provides an alternative reaction pathway with a lower activation energy. Questions 31 and 32 should be answered with reference to the equation 2 C(s) + O2(g) 2 CO(g) ?H < 0 31. What is the equilibrium expression for the reaction represented by the equation above? (A) (C)
K? 2[CO] 2[C]+[O2 ]

25. A device used to test alcohol in the bloodstream uses the reaction 2 K2Cr2O7(aq) + 8 H2SO4(aq) + 3 CH3CH2OH(aq) ? 2 Cr2(SO4)3(aq) + 2 K2SO4(aq) + 3 CH3COOH(aq) + 11 H2O If the rate of disappearance of K2Cr2O7 is 1.24 M/min what is the rate of disappearance of CH3CH2OH? (A) 0.415 M/min (C) 1.86 M/min (B) 0.826 M/min (D) 3.72 M/min

– 26. C(s) + CO2(g) ? 2 CO(g) ?H = 172 kJ?mol 1 In a suitable reaction vessel, pieces of graphite are mixed with carbon dioxide gas at 1.00 atm and 1000 K. Which of the following changes will result in an increase in reaction rate?

(A) decrease size of the graphite pieces (B) decrease temperature (C) decrease partial pressure of CO(g) (D) decrease partial pressure of CO2(g) 27. The reaction CH3NC ? CH3CN is first order. Which reaction characteristic changes as the reaction proceeds? (A) the half life (C) the rate law 28. (B) the rate constant (D) the reaction rate

(B) (D)

K?

2[CO] [O2 ]

K?

[CO]2 [C]2 [O2 ]

K?

[CO]2 [O2 ]

A(g) + B(g) ? C(g) The data below were obtained for the reaction between A and B. What is the rate law for this reaction?
Trial [A]0 (mol?L–1) [B]0 (mol?L–1) Initial Rate of Reaction (mol?L–1? s–1)

32. If the reaction is at equilibrium with excess C(s) remaining, what change will increase the quantity of CO(g) for the reaction at equilibrium? I Adding C(s) II Increasing the temperature III Increasing the pressure (A) I only (C) I, II, and III (B) III only (D) None of these

1 2 3

0.10 0.20 0.10

0.10 0.10 0.20

6.5 × 10 – 2.6 × 10 4 – 6.5 × 10 5

–5

33. An endothermic reaction has a positive value for ?S. Which of the following is true about the equilibrium constant for this reaction? (A) It may be greater than 1 only at low temperatures. (B) It may be greater than 1 only at high temperatures. (C) It is greater than 1 at all temperatures. (D) It is less than 1 at all temperatures.

(A) Rate = k[A] (C) Rate = k[A]2

(B) Rate = k[A][B] (D) Rate = k[A]2[B]

Property of ACS USNCO – Not for use as USNCO Local Section Exam after March 31, 2014

Page 5

34. Phosphoric acid, H3PO4, establishes the following equilibria in aqueous solution. – H3PO4(aq) + H2O(l) H3O+(aq) + H2PO4 (aq) H2PO4 (aq) + H2O(l) – HPO42 (aq) + H2O(l) What is the relationship among the K values? (A) K1 = K2 = K3 (C) K1 > K2 > K3
– – H3O (aq) + HPO42 (aq) – H3O+(aq) + PO43 (aq)
+

40. K1 K2 K3

Half-Reaction Zn2+(aq) + 2 e–→ Zn(s) Cr3+(aq) + 3 e–→ Cr(s) Fe2+(aq) + 2 e– → Fe(s)

E° (V) –0.76 –0.744 –0.409

(B) K1 > K2 = K3 (D) K1 < K2 < K3

Use the E° values in the table above to determine which of the following reactions will give the highest potential in a voltaic cell. (A) 3 Zn2+(aq) + 2 Cr(s) → 3 Zn(s) + 2 Cr3+(aq) (B) 3 Zn(s) + 2 Cr3+(aq) → 3 Zn2+(aq) + 2 Cr(s) (C) Zn2+(aq) + Fe(s) → Zn(s) + Fe2+(aq) (D) Zn(s) + Fe2+(s) → Zn2+(aq) + Fe(s) 41. The cell potential for the voltaic cell depicted below is 0.109 V under standard conditions, 1M Ni2+(aq) and 1 M Pb2+(aq).

35. Which pair of solutes could be used to prepare an aqueous buffer solution with a pH < 7? (A) HCl – NH4Cl (C) NH3 – NH4Cl (B) HF – NaF (D) NaOH – NaCl

36. What will be the result when 15.0 mL of 0.040 M lead(II) nitrate is mixed with 15.0 mL of 0.040 M sodium chloride? – – PbCl2(s) Pb2+(aq) + 2 Cl (aq) [Ksp = 1.7 × 10 5] (A) A clear solution with no precipitate will result. (B) Solid PbCl2 will precipitate and excess Pb2+ ions will remain in solution. (C) Solid PbCl2 will precipitate and excess Cl– ions will remain in solution. (D) Solid PbCl2 will precipitate and no excess ions will remain in solution. 37. What is the oxidation number of As in the compound K(NH4)2AsO4?6H2O? (A) –3 (B) +1 (C) +3 (D) +5

anode cathode Which change will increase the voltage? (A) The 1 M Ni2+ solution is diluted with H2O. (B) A larger Ni electrode is used. (C) 50 mL of 1 M NaCl solution is added to precipitate PbCl2. (D) More 1 M Pb2+ solution is added to that half-cell. 42. Aluminum is produced commercially by the electrolysis of Al2O3. How many hours would be required to produce 250. g of Al using a 5.00 Ampere current? (A) 49.7 (B) 149 (C) 745 (D) 4020

38. When the equation – – – __ MnO4 + __ SO32 + __ H+ ? __ Mn2+ + __ SO42 + __ H2O is balanced correctly with the smallest whole number coefficients, what is the coefficient for H2O? (A) 3 39. (B) 5 (C) 8 (D) 10 E° (V) 0.00 0.90 1.23

Half-Reaction 2 H+ + 2 e – ? H2 Pd2+ + 2 e– ? Pd O2 + 4 H+ + 4 e– ? 2 H2O

43. A sulfur atom in its ground state has the electron configuration 1s2 2s2 2p6 3s2 3p4 How many orbitals are occupied by at least one electron? (A) 3 (B) 5 (C) 8 (D) 9

44. For which of the following transitions would a hydrogen atom absorb a photon with longest wavelength? (A) n = 1 to n = 2 (C) n = 5 to n = 6 (B) n = 3 to n = 2 (D) n = 7 to n = 6

According to the equations and data in the table above, which species is the strongest reducing agent of the following choices? (A) H+ (B) H2 (C) H2O (D) Pd2+

Page 6

Property of ACS USNCO – Not for use as USNCO Local Section Exam after March 31, 2014

45. Which set of quantum numbers is not possible? (A) n = 2, l = 1, ml = +1, ms = –? (B) n = 3, l = 2, ml = +1, ms = +? (C) n = 4, l = 4, ml = –1, ms = +? (D) n =5, l = 2, ml = 2, ms = –? 46. What property of the oxygen atom is represented by the equation O(g) + e– ? O–(g)? (A) electronegativity (C) first ionization energy (B) first electron affinity (D) lattice energy

54. Which molecule is correctly matched with its shape as predicted by VSEPR theory? (A) PCl3 (B) OF2 (C) ClF3 (D) SF6 trigonal pyramidal linear trigonal planar hexagonal

55. Which of the following statements regarding structural isomers is correct? They have (A) the same molecular formula but the atoms are bonded in different ways. (B) the same molar mass but different atoms in their composition. (C) the same physical properties but different chemical properties. (D) different isotopes in their structures. 56. What is the IUPAC name for the compound CH3CH2CH2CH2CHO? (A) pentanal (C) 1-pentanol (B) pentanoic acid (D) 1-pentanone

47. Which of the following isoelectronic species has the largest radius? (A) K+ (B) Ca2+ (C) P3– (D) S2–

48. Which group best illustrates the transition from nonmetallic to metallic behavior with increasing atomic number? (A) Be, Mg, Ca, Sr (C) F, Cl, Br, I (B) N, P, As, Sb (D) Fe, Ru, Os, Hs

49. Which atom is least likely to violate the octet rule in its compounds? (A) B (B) Cl (C) F (D) H

57. Which compound will react rapidly with Br2? (A) benzene (C) 1-hexene (B) hexane (D) 1-hexanol

50. In the Lewis structure for formic acid, HCOOH, how many bonding pairs and lone pairs of electrons are present? (A) 4 bonding, 2 lone (C) 5 bonding, 0 lone (B) 4 bonding, 5 lone (D) 5 bonding, 4 lone

58. The reaction below is best classified as

51. Which ionic compound has the largest lattice energy? (A) LiF (B) BeO (C) KBr (D) CaS

(A) addition. (C) neutralization.

(B) esterification. (D) saponification.

52. When 1.0 mole of H2O2 decomposes to form H2O and O2, 103 kJ of energy is released. Given the bond energies below, what is the bond energy of the O–O single bond in H2O2? Bond Bond Energy, kJ?mol (A) +395 kJ?mol–1 (C) +146 kJ?mol–1
–1

59. Which element is not found in common amino acids? (A) hydrogen (C) oxygen (B) nitrogen (D) phosphorus

H–O 463

O=O 498

60. Which of the following is not classified as a carbohydrate? (A) glucose (C) lactose (B) glycine (D) starch

(B) +249 kJ?mol–1 (D) +103 kJ?mol–1

53. Which species has a different number of pi bonds than the others? (A) C2H2 (B) CO2 (C) N2 (D) O3

END OF TEST

Property of ACS USNCO – Not for use as USNCO Local Section Exam after March 31, 2014

Page 7

Olympiad 2014 USNCO Local Section Exam KEY

Number 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30.

Answer D C B C D A C A B B A A D A C D D C D B B B A C C A D C B D

Number 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50. 51. 52. 53. 54. 55. 56. 57. 58. 59. 60.

Answer D D B C B A D A B D A B D C C B C B C D B C D A A A C B D B


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