Question
Which of the following is an example of a
theory?
a) Solution A is a darker red color than
solution B.
b) All matter is composed of tiny,
indivisible particles called atoms.
c) The grass is green.
d) The temperature of the water is 45°C.
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Answer
b) All matter is composed of tiny,
indivisible particles called atoms.
A theory is a tested explanation of basic
natural phenomena. The other potential
answers are observations.
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Question
A solution is also a
a)
b)
c)
d)
e)
heterogeneous mixture.
homogeneous mixture.
compound.
distilled mixture.
pure mixture.
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Answer
b) homogeneous mixture.
Solutions can be liquids in liquids (such as
rubbing alcohol, which includes isopropanol in
water), solids in liquids (such as sugar water), a
mixture of gases (such as air), or even a
mixture of solids (such as brass, which is a
mixture of copper and zinc).
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Question
Which of the following statements is false?
a) Solutions are always homogeneous
mixtures.
b) A hypothesis is a tentative explanation
of experimental results.
c) Elements can exist as atoms or
molecules.
d) Compounds can exist as individual
atoms or as atoms that are chemically
combined.
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Answer
d) Compounds can exist as individual
atoms or as atoms that are chemically
combined.
Elements can be individual atoms (such
as He) or atoms that are chemically
combined (such as O2), but compounds
are combinations of two or more
elements, so they can never exist as
atoms.
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Question
Which of the following is an example of a
chemical property?
a)
b)
c)
d)
Mercury has a density of 13.6 g/mL.
Oxygen is a gas at room temperature.
The grass is green.
Sodium metal is very reactive.
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Answer
d) Sodium metal is very reactive.
A chemical property describes the
characteristics of a material involving a
chemical change.
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Question
The boiling point of a liquid was measured in the lab, and
the following results were obtained:
Trial
1
2
3
Boiling Point
22.0°C ± 0.1
22.1°C ± 0.1
21.9°C ± 0.1
The actual boiling point of the liquid is 28.7°C. The
results of the determination of the boiling point are
a)
b)
c)
d)
accurate and precise.
precise but inaccurate.
accurate but imprecise.
inaccurate and imprecise.
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Answer
b) precise but inaccurate.
The measurements are precise because
they are all in close agreement with one
another. However, they are relatively far
from the true value, so they are
inaccurate.
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Question
_______ is the agreement of a particular
value with the true value.
a)
b)
c)
d)
e)
Certainty
Precision
Accuracy
Systematic error
Random error
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Answer
c) Accuracy
If a measurement is in close agreement
with the true value, it is an accurate
measurement.
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Question
The glassware shown to the right is called
a buret. The buret is filled to the zero
mark (at the top) with a solution and the
solution is transferred to a beaker. What
volume of transferred solution should be
reported?
a)
b)
c)
d)
e)
20 mL
22 mL
22.0 mL
22.00 mL
28 mL
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Answer
c) 22.0 mL
In a measurement we always include one
uncertain digit. The graduations on this
buret are 1-mL graduations, so we can
estimate the tenths place.
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Question
After calculating an answer in the lab, the
number on your calculator reads
“0.023060070.” If the number is to have five
significant figures, what result should you
report?
a)
b)
c)
d)
e)
0.0230
0.00231
0.023060
0.2367
0.02306
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Answer
c) 0.023060
The leading zeros (to the left of the 2) are
not significant, but the captive zero
(between the 3 and the 6) and terminal
zero (to the right of the 6) are significant.
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Question
How many significant figures are in the
number 0.03040?
a)
b)
c)
d)
e)
One
Two
Three
Four
Five
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Answer
d) Four
The leading zeros (to the left of the 3) are
not significant, but the captive zero
(between the 3 and the 4) and terminal
zero (to the right of the 4) are significant.
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Question
Express 3140 in scientific notation.
a)
b)
c)
d)
3.14 × 103
3.14 × 10−3
3.140 × 103
3.140 × 10−3
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Answer
a) 3.14 × 103
103 = 1000, and 3.14 × 1000 = 3140. We lose
the zero because it is not significant (it is a
placeholder). If the zero were significant we
should write the number as “3140.”.
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Question
Which of the following describes an exact
number?
a)
b)
c)
d)
A basketball has a diameter of 9.39 inches.
There are 60 seconds in a minute.
π = 3.1415.
A student walked 10 minutes to get to class.
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Answer
b) There are 60 seconds in a minute.
Quantities that are derived from the
definition of a unit are exact numbers.
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Question
The beakers below have different precisions as shown.
You pour the water from these three beakers into one
container. What should be the volume in the container
reported to the correct number of significant figures?
a)
b)
c)
d)
78.817 mL
78.82 mL
78.8 mL
79 mL
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Answer
d) 79 mL
In a measurement we always include one uncertain digit.
So, the first measurement can be 26.4 mL ± 0.1 mL, the
second can be 26 mL ± 1 mL, and the third can be 26.42
mL ± 0.01 mL. When adding, the result has the same
number of decimal places as the least precise
measurement, in this case, to the ones place. So the
answer is 26.4 + 26 + 26.42 = 78.82 mL, which must be
rounded to 79 mL.
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Question
Which of the following is not an example
of a derived quantity?
a)
b)
c)
d)
e)
Pressure
Area
Density
Volume
Length
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Answer
e) Length
Derived quantities are combinations of
base units. Pressure is force per unit area
(such as kg/(m.s2)), area is volume
squared (such as m2), density is mass per
unit volume (kg/m3), and volume is length
cubed (such as m3).
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Question
Convert 5.853 kg to milligrams.
a) 5.853 mg
b) 5853 mg
c) 5.853 × 106 mg
d) 5.853 × 10−6 mg
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Answer
c) 5.853 × 106 mg
The number of milligrams is larger than the
number of kilograms because a kilogram is
larger than a milligram. There are 1000 g/kg
and 1000 mg/g, so the number of milligrams per
kilogram is
103 g/kg x 103 mg/g = 106 mg/kg.
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Question
Ethylene glycol has a density of 1.114 g/mL.
What volume must be poured into a graduated
cylinder to give 21.1 g of ethylene glycol?
a)
b)
c)
d)
e)
0.0528 mL
18.9 mL
18.94 mL
23.5 mL
23.51 mL
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Answer
b) 18.9 mL
Since d = m/V, the formula can be rearranged
to give V = m/d. Substituting in the values gives
21.1 g
V =
= 18.9 mL
g
1.114
mL
The number of significant figure in the answer is
three because the mass has only three
significant figures.
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