Modified True/False
Indicate
whether the sentence or statement is true or false. If false,
change the identified word or phrase to make the sentence or statement
true.
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1. |
In
a balanced chemical equation, the total mass of reactants equals
the total mass of products. ____________________
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2. |
One
mole of NH3(g) molecules contains one mole of nitrogen atoms
and three moles of hydrogen atoms. ____________________
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3. |
One
mole of CO2(g) molecules contains 6.02 ´ 1023 CO2(g)
molecules. ____________________
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4. |
The
atomic mass unit is equal to the mass of 12 carbon-12 atoms.
____________________
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5. |
The
isotopes of an element differ by the number of protons in the
nucleus. ____________________
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6. |
If
the atomic mass of chlorine is 35.5 u/atom, the molar mass of chlorine
is 35.5 g/mol. ____________________
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7. |
Molecular elements contain two or more atoms of the same element.
____________________
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8. |
The
law of constant composition states that compounds contain atoms in fixed
proportions. ____________________
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9. |
A
combustion analyzer measures the molar mass of a compound. ______________________________
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10. |
The
information provided by a combustion analyzer and mass spectrometer
may be used to determine the molecular formula of a compound.
____________________
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11. |
If
the molecular formula of a compound is C3H8NS,
then its empirical formula is also C3H8NS.
____________________
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Multiple Choice
Identify
the letter of the choice that best completes the statement or answers
the question.
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12. |
What
amount of carbon dioxide is in 17.6 g of carbon dioxide?
a. |
5.87
mol |
c. |
0.40
mol |
b. |
2.5
mol |
d. |
0.55
mol |
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13. |
The
molar mass of methanol, CH4O(l), is
a. |
28.0
g/mol |
c. |
29.0
g/mol |
b. |
31.0 g/mol |
d. |
32.0 g/mol |
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14. |
The
molar mass of calcium phosphate, Ca3(PO4)2(s),
is
a. |
278
g/mol |
c. |
247
g/mol |
b. |
310 g/mol |
d. |
199 g/mol |
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15. |
The
mass of 3.75 mol of KF(s) is
a. |
3.75 g |
c. |
217.8 g |
b. |
58.1
g |
d. |
108.9
g |
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16. |
What
amount of iron is in 5.00 mol of FeO(s)?
a. |
5.00
mol |
c. |
1.00
mol |
b. |
10.00
mol |
d. |
2.50
mol |
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17. |
How
many molecules of NO(g) are in 16.0 g of NO(g)?
a. |
3.21
´
1023 |
c. |
1.81
´
1025 |
b. |
9.63 ´ 1024 |
d. |
6.02 ´ 1023 |
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18. |
Which
of the following elements contains the greatest number of atoms in a
5.00-g sample?
a. |
lithium |
c. |
potassium |
b. |
sodium |
d. |
rubidium |
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19. |
Which
of the following samples contains the same number of atoms as 40.00
g of Ne(g)?
a. |
4.00
g of He(g) |
c. |
40.00
g of C(s) |
b. |
24.00 g of Mg(g) |
d. |
80.00 g of Ar(g) |
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20. |
How
many molecules are in 0.25 mol O2(g)?
a. |
12 ´ 1023 |
c. |
3.0 ´ 1023 |
b. |
6.0
´
1023 |
d. |
1.5
´
1023 |
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21. |
What
is the mass of iron in 1.00 mol Fe2O3(s)?
a. |
160
g |
c. |
72.0
g |
b. |
112
g |
d. |
56.0
g |
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22. |
How
many oxygen atoms are in 49.0 g of H2SO4(aq)?
a. |
2.4
´
1024 |
c. |
3.01
´
1023 |
b. |
6.02 ´ 1023 |
d. |
1.2 ´ 1024 |
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23. |
Which
of the following statements is incorrect?
a. |
One mole of ozone has a mass of 48.0 g. |
b. |
One
mole of methane, CH4(g), contains 6.02 ´ 1023 carbon atoms. |
c. |
12.01
g of carbon has the same number of atoms as 12.01 g of nitrogen. |
d. |
One
mole of a substance is the amount of the substance that has the
same number of entities as 12.00 g of carbon-12. |
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24. |
Which
of the following entities has the greatest mass?
a. |
one atom of aluminum |
c. |
one atom of phosphorus |
b. |
one
molecule of fluorine |
d. |
one
molecule of methane |
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25. |
A
mass spectrometer measures
a. |
the percentage of elements in a compound |
b. |
the molar mass of a compound |
c. |
the
number of ions in an ionic compound |
d. |
the charge on an ion |
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26. |
The
empirical formula of a compound is CH. Its molar mass is 78.0 g/mol.
What is its molecular formula?
a. |
CH |
c. |
C12H12 |
b. |
C6H6 |
d. |
C2H6 |
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27. |
The
percentage composition by mass of a compound is 52.16% carbon, 7.29%
hydrogen, and 40.55% nitrogen. Its molar mass is 138.20 g/mol. What
is the molecular formula of the compound?
a. |
C8H14N2 |
c. |
C6H10N4 |
b. |
C7H12N3 |
d. |
C3H5N2 |
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28. |
What
is the percentage by mass of chlorine in hypochlorous acid, HClO(aq)?
a. |
46.71% |
c. |
30.52% |
b. |
23.40% |
d. |
67.58% |
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29. |
What
is the percentage by mass of nitrogen in Cu(NO3)2(s)?
a. |
14.93% |
c. |
50.61% |
b. |
33.88% |
d. |
44.40% |
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Completion
Complete each sentence
or statement.
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30. |
The
number 6.02 ´ 1023 is equivalent to ____________________
constant.
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31. |
The
term ____________________ specifically refers to the number of moles
of chemical entities in a quantity of matter.
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32. |
When
working with chemical entities, the mole is a reasonable quantity because
this quantity can be ____________________ and ____________________.
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33. |
The
____________________ number of an element is equal to
the number of protons in the nucleus.
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34. |
The
atomic molar mass of an element is equal to the mass, in grams, of one
____________________ of atoms of the element.
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35. |
Chemists determine the amount of a chemical entity in a pure sample
by measuring the ____________________ of the sample.
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36. |
The
empirical formula of a compound describes the ____________________ ratio
of atoms or ions in a compound
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