2000
Chemistry
Example

(c) ACS High School Chemistry Scholarship Exam
Questionario a risposta multipla di chimica


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1. Which one of the following is the largest distance?
a. 10 microL
b. 2 km
c. 1x104 mm
d. 1 kPa
2. When the number 0.0640510 is rounded to three significant figures, it is reported as:
a. 0.06
b. 0.064
c. 0.0641
d. 0.06405
3. Report the answer to the following mathematical operations using the correct number of significant figures.
15.32 - 8.2
7.84
a. 0.9
b. 0.91
c. 0.908
d. 0.9082
4. The yellow light emitted by a sodium vapor lamp has a wavelength equal to 589 nm. What is the frequency of this radiation?
a. 5.09x1014s-1
b. 1.96x103 s-1
c. 0.0509 s-1
d. 1.96x10-15 s-1
5. Which of the following are chemical changes?
(I) baking bread (IV) dissolving sugar in water
(II) melting solder (V) lighting a match
(III) breaking of glass
a. I, V
b. II, III, IV
c. I, II, V
d. II, IV, V
6. How many square inches are in 53.6 m2?
a. 3.46x102 in2
b. 4.68x104 in2
c. 8.31x104 in2
d. 2.11x103 in2
7. How many protons, neutrons, and electrons are contained in the nuclide 5324Cr3+?
a. 24 protons, 29 neutrons, 27 electrons
b. 24 protons, 26 neutrons, 21 electrons
c. 24 protons, 29 neutrons, 21 electrons
d. 29 protons, 24 neutrons, 26 electrons
8. Which one of the following formulas correctly matches its name?
a. BaSO3 barium sulfite
b. KSO4 potassium sulfate
c. Na2S disodium hyposulfite
d. CuSO4 copper(I) sulfate
9. An element X combines with sulfur to form a compound having the formula X2S3. X could be:
a. Ba
b. Rb
c. Si
d. Al
10. The normal boiling point of liquid nitrogen is 77.35 K. What is the boiling point of nitrogen in oF?
a. -76.78 oF
b. -171.2 oF
c. -320.4 oF
d. -384.4 oF
11. What is the formula of iron(II) hydrogen phosphate?
a. Fe(HPO4)2
b. FeHPO4
c. Fe(H2PO4)2
d. Fe2HPO4
12. What is the correct formula for the compound magnesium nitrate?
a. Mg(NO3)2
b. MgNO2
c. Mg(NO2)3
d. Mn(NO3)2
13. What is the correct empirical formula of the compound C8H16O4?
a. C4H8O2
b. C8H16O4
c. C2H4O2
d. C2H4O
14. If 0.50 mole C8H16O4 is completely decomposed into its constituent elements, how many moles of hydrogen gas (H2) would be produced?
a. 16.0 moles
b. 8.0 moles
c. 4.0 moles
d. 0.5 moles
15. If 0.50 mole C8H16O4 is completely decomposed into its constituent elements, how many grams of carbon would be produced?
a. 96 g
b. 48 g
c. 4.8 g
d. 4.0 g
16. What is the formula mass of magnesium phosphite, Mg3(PO3)2?
a. 71.7
b. 182.3
c. 230.9
d. 309.9
17. When 33.0 mg of an unknown compound was submitted for elemental analysis, it contained 21.60 mg carbon (C), 3.00 mg hydrogen (H), and 8.40 mg nitrogen (N). What is the empirical formula of this unknown compound?
a. C3H5N
b. C1.8H3N0.6
c. C7H14N3
d. C18H30N6
18. When the equation below is properly balanced, what is the coefficient of barium chloride (BaCl2)?
AlCl3(aq) + Ba3(PO4)2(aq) AlPO4(s) + BaCl2(aq)
a. 2
b. 3
c. 4
d. 6
19. When 22.34 g iron (Fe, atomic mass = 55.85) is consumed in the following reaction, how many grams of hydrogen gas will be produced?
6 HNO3(aq) + 2 Fe(s) 3 H2(g) + 2 Fe(NO3)3(aq)
a. 0.600 g
b. 0.798 g
c. 1.200 g
d. 33.51 g
20. When 14.0 g cyclohexane reacts with 14.0 g chlorine
C6H12(s) + Cl2(g) C6H11Cl(s) + HCl(g)
Substance
C6H12
Cl2
C6H11Cl
Molecular weight
84.0
70.9
118.5
what is the maximum number of grams of chlorocyclohexane which could be produced?
a. 19.75 g
b. 21.00 g
c. 23.40 g
d. 43.15 g
21. How many grams of calcium bromide (CaBr2, MW = 200.) must be used to prepare 500. mL of 0.400 M CaBr2 solution?
a. 20.0 g
b. 40.0 g
c. 60.0 g
d. 80.0 g
22. What is the concentration of the final solution when 500. mL of 0.400 M CaBr2 solution is diluted to 1.60 L?
a. 0.125 M
b. 0.400 M
c. 1.28 M
d. 25.0 M
23. What is the concentration of the solution obtained when 200. mL of a 0.600 M solution of sulfuric acid (H2SO4, MW = 98.1) is added to 400. mL of a 1.2 M solution of sulfuric acid to make a total volume of 600. mL?
a. 0.200 M
b. 0.800 M
c. 0.480 M
d. 1.00 M
24. What is the concentration of a solution of hydrochloric acid if 37.50 mL of a 0.200 M solution of sodium hydroxide is necessary to neutralize a 50.00 mL aliquot?
Substance
HCl
NaOH
Molecular weight
36.5
40.0
a. 0.267 M
b. 0.205 M
c. 0.188 M
d. 0.150 M
25. Which of the following 0.10 M aqueous solutions would have the lowest freezing point?
a. KBr
b. Na2SO4
c. NaNO3
d. MgSO4
26. The molar mass of hemoglobin is 68,000 g/mol. Calculate the osmotic pressure produced from 2.20 g hemoglobin in 100. mL water at 20oC. [R = 0.0821 L atm/(mol K)]
a. 5.29x10-3 atm
b. 7.78x10-3 atm
c. 5.29x10-4 atm
d. 7.78x10-4 atm
27. The First Law of Thermodynamics can be represented as:
a.
S=
H
T
b.PV=nRT
c. w=-PV
d. E = q + w
28. Which of the following describes bromine at room temperature?
a. reddish-brown liquid
b. greenish-yellow liquid
c. greenish-yellow gas
d. violet gas
29. Given the following two reactions:
C(graphite) + O2(g) CO2(g)    H = -393.5 kJ

2 Fe(s) + 3/2 O2(g) Fe2O3(s)    H = -824.2 kJ

Calculate the enthalpy change for
2 Fe2O3(s) + 3 C(graphite) 4 Fe(s) + 3 CO2(g)
a. H = +467.9 kJ
b. H = -467.9 kJ
c. H = +430.7 kJ
d. H = -430.7 kJ
30. The symbol for cesium is
a. Ce
b. Cm
c. Cs
d. Se
31. What do phosphorus, sulfur and oxygen have in common?
a. outer shell electron configuration
b. pyrophoric behavior
c. semimetallic behavior
d. existence of allotropic forms
32. What is the name of the product of the following reaction:
2 K(s) + O2(g) K2O2(s)
a. potassium dioxide
b. potassium peroxide
c. potassium oxide
d. potassium superoxide
33. What is the temperature change when 4.00 g Fe absorbs 55.5 J? [specific heat of Fe = 0.4998 J/g?oC]
a. 27.8oC
b. 55.5oC
c. 111.0oC
d. insufficient information
34. The combustion of methane is given by the following reaction:

CH4(g) + 2 O2(g) CO2(g) + 2 H2O(aq)    H = -890.4 kJ

How much heat is evolved in the combustion of 2.00 g methane?

a. 55.7 kJ
b. 111 kJ
c. 890. kJ
d. 1780 kJ
35. Which one of the following electron configurations represents Cr2+?
a. [Ar]4s23d4
b. [Ar]4s23d2
c. [Ar]3d4
d. [Ar]3d2
36. Which of the following most likely represents a negative entropy change?
a. H2O(aq) H2O(g)
b. MgCO3(s) MgO(s) + CO2(g)
c. Zn(s) + 2 HCl(aq) ZnCl2(aq) + H2(g)
d. NaCl(aq) + AgNO3(aq) NaNO3(aq) + AgCl(s)
37. Which of the following has the highest boiling point?
a. CH3CH2OH
b. CH3CH2CH2OH
c. CH3CH2CH2CH3
d. CH3CH2OCH3CH2
38. Which of the following elements has the lowest first ionization energy?
a. antimony
b. arsenic
c. nitrogen
d. phosphorus
39. Which of the following isoelectronic species is the largest?
Kr Rb+ Se2- Sr2+
a. Kr
b. Rb+
c. Se2-
d. Sr2+
40. The chemical properties of an element correlate best with
a. its state of matter.
b. ionic radii.
c. atomic weight.
d. electron configuration.
41. Arrange the following radiation in order of increasing energy.
microwave ultraviolet green light orange light
a. microwave < orange light < green light < ultraviolet
b. ultraviolet < microwave < green light < orange light
c. orange light < green light < microwave < ultraviolet
d. ultraviolet < green light < orange light < microwave
42. Which of the following bonds is the most polar?
a. H-H
b. H-C
c. C-F
d. C-Cl
43. Which of the following compounds is most ionic?
a. N2O
a. Cl2O7
a. P2O5
a. Na2O
44. Which of the following terms best describes CaO?
a. an acidic oxide
b. a basic oxide
c. an amphoteric oxide
d. a neutral oxide
45. Which element below has the most metallic character?
a. As
b. Sb
c. P
d. Bi
46. Which elements combine with the alkali metals to form ionic compounds?
a. alkaline earth metals
b. d-transition series elements
c. noble gases
d. halogens
47. What is the formal charge on the indicated nitrogen in the neutral molecule below?
N=N=O
a. 0
b. -1
c. +1
d. +2
48. What do the following species have in common?
CS2 CO2 CH2O
a. All are gases are room temperature.
b. All contain pi (p) bonding.
c. All are isoelectronic with each other.
d. All have no dipole moment.
49. How many lone pairs are found in the entire molecule PBr5?
a. none
b. 5
c. 15
d. 20
50. A molecule has the following properties:
  • The molecule contains two different halogens.
  • The molecule has no dipole moment.
  • The molecule does not form hydrogen bonds.
What molecule could it be?
a. OF2
b. IBr3
c. PCl2Br
d. IBr4-
51. Predict the order for increasing O-O bond energy of the species

O2 O2+ O22-

a. O2 < O22- < O2+
b. O2+ < O22- < O2
c. O2 < O2+ < O22-
d. O22- < O2 < O2+
52. Pi bonding can be found in which of the following?
a. carbon monoxide
b. acetone
c. sulfur dioxide
d. All of the above molecules contain pi bonding.
53. Linear geometry best describes which of the following molecules?
a. acetylene
b. ozone
c. hydrogen peroxide
d. All of the above molecules are linear.
54. How many sigma and pi bonds does formaldehyde (CH2O) have?
a. 3 sigma bonds and no pi bond
b. 3 sigma bonds and 1 pi bond
c. 2 sigma bonds and 1 pi bond
d. 2 sigma bonds and 2 pi bonds
55. A molecule can be described by the following major characteristics:
  • The molecule contains at least one sp2 hybrid orbital.
  • The molecule contains at least one sp hybrid orbital.
  • The molecule contains no triple bonds.
Which molecule could it be?
a. C2H2 (acetylene)
b. C3H4 (allene)
c. C6H6 (benzene)
d. C6H5OH (phenol)
56. An example of a paramagnetic species (one that is drawn into a magnetic field) is
a. ozone.
b. the cyanide ion, CN-.
c. the fluorine molecule.
d. the oxygen molecule.
57. A 4.0 L flask contains 0.40 moles each of He, CH4 and H2S at a total pressure of 6.0 atm. What is the partial pressure of methane?
a. 1.0 atm
b. 1.5 atm
c. 2.0 atm
d. 2.4 atm
58. If 148 g SnO2 (MW = 150.69) are reacted with excess carbon at 0oC and 1.0 atm, what volume of carbon dioxide is evolved?

SnO2(s) + C(s) CO2(g) + Sn(s)
a. 1.0 L
b. 11 L
c. 22 L
d. 150 L
59. A 1.0 L sealed flask contains He(g) and N2(g). Does He or N2 have the highest average molecular speed?
a. He
b. N2
c. They have the same average molecular speed.
d. There is insufficient information given to answer the question.
 
The following information applies to questions 60 and 61.

An experiment is performed in which 1.0 J of heat is added to 10. g ethanol (C2H5OH). The same amount of heat is added to 10. g benzene (C6H6) and the following temperature changes are observed:

Substance T
ethanol +0.041 K
benzene +0.057 K

60. Which compound has the larger specific heat?
a. ethanol
b. benzene
c. They have the same specific heat.
d. It cannot be determined from the information given.
61. Which has the larger molar heat capacity?
a. ethanol
b. benzene
c. They have the same molar heat capacity.
d. It cannot be determined from the information given.
62. A 0.020 mole sample of argon has a pressure of 0.50 atm and a temperature of 20.oC. What volume does it occupy?
a. 0.024 L
b. 0.48 L
c. 0.96 L
d. 22 L
63. If 1.0 L each of oxygen and hydrogen are reacted at constant temperature and pressure, how much water vapor will be produced?
a. 1.0 L
b. 2.0 L
c. 0.5 L
d. 4.0 L
64. The unit cell for nickel metal is face-centered cubic. If the radius of a nickel atom is 1.24 Å what is the length of a side of the nickel unit cell?
a. 2.23 Å
b. 2.48 Å
c. 3.51 Å
d. 4.96 Å
65. Polonium crystallizes in a primitive cubic unit cell with side length a = 3.36 Å. What is the density of polonium?
a. 9.15 g/cm3
b. 9.15x10-24 g/cm3
c. 1.03x10-14 g/cm3
d. 1.03 g/cm3
66. The rise of a liquid in a thin tube against the force of gravity is called
a. capillary action.
b. dispersion forces.
c. surface tension.
d. viscosity.
67. The higher boiling point of ethanol over pentane is predominantly due to
a. intertwining of molecules in pentane.
b. higher molecular weight of pentane.
c. van der Waals repulsion in ethanol.
d. hydrogen bonding in ethanol.
68. The strongest intermolecular force between Xe atoms is the
a. nuclear force.
b. dipole-dipole force.
c. hydrogen bonding force.
d. dispersion (London) force.
69. Ethanol dissolves in both water and benzene. Which best describes the characteristics of the ethanol molecules ?
a. very polar
b. moderately polar
c. nonpolar
d. hydrophobic
70. An aqueous solution of calcium chloride is 15.0% by mass CaCl2. If the solution has a density of 1.12 g/mL, what is the molarity of the solution?
a. 1.28 M
b. 1.35 M
c. 1.51 M
d. 1.68 M
71. Which of the following has the lowest boiling point?
a. F2
b. Cl2
c. Br2
d. I2
72. An endothermic process always
a. corresponds to a negative enthalpy change.
b. involves an absorption of heat by the system.
c. corresponds to a temperature increase.
d. involves a release of heat by the system.
73. What is the missing particle in the following nuclear equation?

9842Mo + 21H 10n + ?
a. Nb
b. Es
c. Tc
d. Cm
74. The reaction A Z is a first order reaction. The rate constant, k, for the reaction is 0.10 s-1 and the initial concentration of A is 1.0x10-2 M. Determine how much time in seconds it will take for the concentration of A to drop to 5.0x10-3 M. [k = 0.693/t1/2]
a. 50. ms
b. 6.9 s
c. 10. s
d. 14 s
75. The half-life of radon, 22286Rn, is 3.82 days. Determine the length of time required for 112 g of radon to decay to 28.0 g.
a. 3.82 days
b. 5.73 days
c. 7.64 days
d. 11.5 days
76. The rate law for the following reaction

2 NO(g) + Br2 2 NOBr

is given by rate = k[NO]2[Br2]. If [NO] is increased by a factor of three while [Br2] is held constant, the initial rate of the reaction will:

a. increase by a factor of two
b. increase by a factor of three
c. increase by a factor of eight
d. increase by a factor of nine
77. The gas-phase reaction, Cl2 + CH4 CH3Cl + HCl, proceeds by free-radical Chain propagation. Using the following kinetic data, determine the correct rate equation.
Experiment PCl2 (kPa) PCH4 (kPa) Initial Rate
1 1.0 1.0 1.0x102
2 1.0 2.0 2.0x102
3 4.0 2.0 4.0x102
a. Rate = k[Cl2]1/2[CH4]
b. Rate = k[Cl2][CH4]
c. Rate = k[Cl2]2[CH4]
d. Rate = k[Cl2][CH4]2
78. Chlorine atoms photochemically derived from freons help deplete stratospheric ozone in the two-step mechanism below:

Cl + O3 ClO + O2
ClO + O Cl + O2

The respective species Cl and ClO for the overall balanced reaction are

a. both intermediates.
b. both catalysts.
c. intermediate and catalyst.
d. catalyst and intermediate.
79. What is the equilibrium constant expression for the following reaction?

2 NaHSO3(s) Na2SO3(s) + H2O(g) + SO2(g)
a.
[H2O][SO2][Na2SO3]

[NaHSO3]2
a.
[SO2]
b.
[H2O][SO2]
c.
[NaHSO3]2

[Na2SO3][SO2][H2O]
80. A sample of NH3 is placed into a container at 1.00 atm and 25oC and sealed. After equilibrium has been reached, the total pressure inside the container is 1.98 atm. What is the equilibrium constant, Kp, at 25oC?

2 NH3(g) N2(g) + 3 H2(g)
a. 0.028
b. 36
c. 530
d. 3900
81. Kc for the reaction below is 610 at 1600 K. What is the Kp at 1600 K?

NiO(s) + CO(g) Ni(s) + CO2(g)
a. 8.0x104
b. 610
c. 54
d. 1.3x10-5
82. How is the equilibrium constant for an exothermic reaction affected by an increase in temperature of the system?
a. The equilibrium constant becomes larger.
b. The equilibrium constant becomes smaller.
c. There is no change in the equilibrium constant.
d. There is no way to determine the effect.
83. Which of the following will drive the reaction below toward products?

C(s) + CO2(g) 2 CO(g) Ho = 119.8 kJ
a. cooling the reaction system
b. increasing the partial pressure of CO
c. increasing the volume
d. adding more carbon
84. Which of the following is a conjugate acid of HONH2?
a. HONH3+
b. HONH2
c. HONH-
d. HON2-
85. Identify which of the following ions will hydrolyze.

Na+ ClO- Al3+ Br-

a. Na+ and Al3+
b. ClO- and Br-
c. Na+ and Br-
d. ClO- and Al3+
86. What is the pH of a solution of NaOH prepared by dissolving 0.10 g of NaOH in enough water to make 1.0 L of solution?
a. 2.6
b. 7.0
c. 11.4
d. 13.0
87. The Ka of a 0.0050 M HClO solution is 3.0x10-8. What is the pH of the solution?
a. 3.2
b. 4.9
c. 7.5
d. 9.6
88. A 0.010 M solution of acetic acid, HC2H3O2, is titrated to the equivalence point with a 0.0080 M NaOH solution. What is the pH at the equivalence point? The Ka for HC2H3O2 is 1.8x10-5.
a. 3.8
b. 5.2
c. 7.0
d. 8.2
89. When a solution of Mn(NO3)2 is added to a saturated solution of Mn(OH)2,
a. the solubility of Mn(OH)2 increases.
b. the solubility product constant decreases.
c. the pH of the solution decreases.
d. the equilibrium shifts to the product side.
90. The molar solubility of Ag2CrO4 at 25oC is 6.5x10-5. What is the Ksp at 25oC?
a. 2.6x10-4
b. 8.5x10-9
c. 1.1x10-12
d. 2.9x10-16
 
The following reaction applies to questions 91 and 92.

14 H+ + Cr2O72- + 3 Ni 3Ni2+ + 2Cr3+ + 7H2O


91. Identify the oxidizing agent in the reaction above.
a. H+
b. Cr2O72-
c. Ni
d. Cr3+
92. Which substance is oxidized in the reaction above.
a. H+
b. Cr2O72-
c. Cr3+
d. Ni
93. What is the oxidation number of manganese in KMnO4?
a. +3
b. +5
c. +7
d. +9
94. What is the stoichiometric coefficient for ZnS(s) in the following equation when it is correctly balanced? Assume acidic conditions.

ZnS(s) + NO3-(aq) Zn2+(aq) + S(s) + NO(g)
a. 1
b. 2
c. 3
d. 4
95. What is the oxidation number of gold in K3[Au(CN)4]?
a. +1
b. +2
c. +3
d. +4
 


The following information applies to questions 96 and 97.

A voltaic cell consists of a silver electrode dipping into a 1.0 M silver nitrate solution, and a nickel electrode dipping into a 1.0 M Ni(NO3)2 solution. A salt bridge connects the two solutions and the external circuit is a copper wire connecting the two metal electrodes.

Ag+ + e- Ag   Eo = 0.80 V
Ni2+ + 2e- Ni   Eo = -0.28 V


96. Which of the following statements is a true statement?
a. Electrons flow in the external circuit from silver to nickel.
b. The Ag electrode is the anode.
c. Ni2+ is reduced to Ni.
d. Ag+ is reduced to Ag.
97. The standard emf for the cell described above is
a. 1.08 V.
b. 1.36 V.
c. 0.52 V.
d. 0.24 V.
98. Which transformation could take place at the anode of an electrochemical cell?
a. Cr3+ to Cr2O72-
b. F2 to F-
c. PbO2 to Pb4+
d. HAsO2 to As
99. Determine the Ka of the weak acid HA from the information in the graph below.
a. 3.2x10-3
b. 6.3x10-5
c. 5.1x10-6
d. 2.0x10-8
100. Classify the following molecule according to functional group.
a. carboxylic acid
b. ester
c. aldehyde
d. alcohol




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