Download - Chapter 2 Atoms, Molecules, and Ions
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Chemistry, The Central Science, 10th edition
Theodore L. Brown; H. Eugene LeMay, Jr.;and Bruce E. Bursten
Chapter 2Atoms, Molecules,
and Ions
Troy WoodUniversity of BuffaloBuffalo, NY 2006, Prentice Hall
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How many neutrons are there in an atom of 14C?
1. 62. 83. 124. 14
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Correct Answer:
Atomic numberMass number 14
6 CThe difference between the mass number and the atomic number is the number of neutrons (14 6) = 8.
1.6
2.8
3.12
4.14
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An isotope of Cr3+ ion containing 24 protons and 27 neutrons would contain ___ electrons.
1. 21
2. 24
3. 27
4. 3
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Correct Answer:
The +3 charge indicates there are 3 more protons than electrons:
24 3 = 21
1. 21
2. 24
3. 27
4. 3
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A hypothetical element has two isotopes. One of the isotopes has an abundance of 75.0% and a relative mass of 12.0 amu, while the other has an abundance of 25.0% and a relative mass of 14.0 amu. The atomic mass
of this hypothetical element is
1. 12.5 amu.2. 13.0 amu.
3.13.5 amu.4.13.8 amu.
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Correct Answer:
Atomic mass = (0.750)(12.0 amu) + (0.250)(14.0 amu)
Atomic mass = 9.0 amu + 3.5 amu = 12.5 amu
1. 12.5 amu.2. 13.0 amu.
3.13.5 amu.4.13.8 amu.
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Chlorine has two isotopes, 35Cl (75.78% abundant) and 37Cl (24.22% abundant). How many different molar masses are possible for a Cl2 molecule?
1. 22. 33. 44. 5
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Correct Answer:
35Cl2 = 70 amu35Cl37Cl = 72 amu37Cl2 = 74 amu
1. 22. 33. 44. 5
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Which of the following species has the greatest number of electrons?
1. Cl
2. Ca2+
3. P3
4. K5. Ar
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Correct Answer:
K has 19 electrons; all the other species listed have only 18 electrons.
1. Cl
2. Ca2+
3. P3
4. K5. Ar
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The compound, CuSO4, is called
1. Calcium sulfide2. Carbon sulfide3. Calcium sulfite4. Calcium sulfate5. Copper sulfate
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Correct Answer:
The compound is ionic, derived from the copper(II) cation (Cu2+) and the sulfate anion (SO4
2).
1. Calcium sulfide2. Carbon sulfide3. Calcium sulfite4. Calcium sulfate5. Copper sulfate
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The correct name for the compound, MgC2 is
1. Carbon magneside2. Magnesium carbide3. Magnesium carbonate4. Manganese dicarbide5. Magnesium dicarbide
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Correct Answer:
In this unusual ionic compound, the cation is magnesium cation (Mg2+) and the anion is carbide or acetylide (C2
2).
1. Carbon magneside2. Magnesium carbide3. Magnesium carbonate4. Manganese dicarbide5. Magnesium dicarbide
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The simplest chemical formula for the binary ionic compound CaxNy is
1. Ca2N2. Ca2N3
3. Ca3N2
4. Ca3N
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Correct Answer:
Ca loses two electrons to become Ca2+, while N gains three electrons to become N3
. To be neutral, positive charges and negative charges have to balance.
1. Ca2N2. Ca2N3
3. Ca3N2
4. Ca3N
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The ion Cr2O72 is known as:
1. Chromos2. Chromite3. Chromate4. Dichromate5. Bichromite
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Correct Answer:
Dichromate solutions are a deep orange color.
1. Chromos2. Chromite3. Chromate4. Dichromate5. Bichromite
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The acid HClO3 is known as:
ClO
O
HO1. Perchloric acid2. Chloric acid3. Chlorous acid4. Hypochlorous acid5. Hydrochloric acid
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Correct Answer:
ClO
O
HO1. Perchloric acid2. Chloric acid3. Chlorous acid4. Hypochlorous acid5. Hydrochloric acid
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The molecular compound N2O4 is named:
1. Nitrogen oxide2. Oxygen nitride3. Dinitrogen quartoxide4. Dinitrogen tetroxide5. Nitrous oxide
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Correct Answer:
Remember: the vowel “A” on the prefix tetra- is dropped because oxide starts with the vowel “O.”
1. Nitrogen oxide2. Oxygen nitride3. Dinitrogen quartoxide4. Dinitrogen tetroxide5. Nitrous oxide