Chem 300 – Practice Exam 1
True or False
1. _______
The measurement described by pm3 is a volume.
2. _______
The conversion factor for nm to m is 10-9nm = 1 m.
3. _______
4.9 x 10-6 L = 4.9 L
Match the definitions below with the following terms:
a) fact
b) natural law
c) hypothesis
d) theory
4. ______ Generalization that summarizes in a concise way information about natural phenomena.
5. ______
Tentative model or picture that offers an explanation for the behavior of a system.
6. ______
Tentative model that has been tested and validated over long periods of time
7. ______
A valid observation about some phenomenon
8. If the accepted value for the length of an object is 6.78 cm, which of the following sets of experimental results is
best described as both precise and accurate?
a) 6.78 cm, 6.38 cm, 6.48 cm (average = 6.55cm)
b) 6.79 cm, 6.78 cm, 6.77 cm (average = 6.78 cm)
c) 6.71 cm, 6.71 cm, 6.72 cm (average = 6.71 cm)
d) 6.88 cm, 6.88 cm, 6.58 cm (average = 6.78 cm)
9. In which one of the following numbers are none of the zeros significant?
a) 100.03
b) 41,000,000
c) 0.00001470
d) 2.70400
10. A balance has a precision of + 0.0001 grams. Which mass reading below was read from this balance?
a) 49.1009 g
b) 49.10 g
c) 49.10090 g
d) 49.101 g
11. The correct answer obtained from adding the measurements 3.6 + 6.4501 + 0.2301 contains
a) 2 significant figures
b) 3 significant figures
c) 4 significant figures
d) 5 significant figures
12. Perform the indicated mathematical operations and express the answer in scientific notation rounded to the
proper number of significant figures.
(1.44 x 103) x (8.011 x 102) =
(1.2 x 10-3)
a)
b)
c)
d)
e)
9.6 x 102
9.60 x 108
9.601 x 108
9.6 x 108
9.6 x 10-8
13. How do you describe a non-uniform white crystalline substance, part of which dissolves in water and part of
which does not?
a) heterogeneous mixture
b) homogeneous mixture
c) compound
d) element
14. Which of the following conversion factor sequences (for units only) would effect the change from ft/sec to
km/hr?
a) ft x sec x min x m x km
b) ft x sec x min x ft x km
sec min hr
ft
m
sec min hr
m
m
c) ft x m x km x min x hr .
sec ft
m
sec
min
d)
ft x m x m . x sec x min
sec ft
km
min
hr
15. 1.50 cubic feet is equivalent to how many cubic centimeters?
a) 45.7 cubic centimeters
b) 4.25 x 104 cubic centimeters
c) 158 cubic centimeters
d) 0.144 cubic centimeters
16. What is the mass of 25.0 mL of a liquid if its density is 1.74 g/mL?
a) 9.00 g
b) 43.5 g
c) 14.4 g
d) 0.0696 g
17. What is the volume of a solution with a density of 13.9 g/mL is needed to provide 75.0 grams of solution?
a) 5.40 mL
b) 1040 mL
c) 0.185 mL
d) 16.7 mL
18. A cylindrical slug of aluminum has a diameter of 3.86 cm and a height of 15.0 cm. What is the volume of the
cylinder of aluminum?
a) 702 cm3
b) 18.2 cm3
c) 176 cm3
d) 1460 cm3
19. Which one of the following statements about atoms is correct?
a) An atom is the smallest ‘piece’ of an element that can exist and still have the properties of the element.
b) Free isolated atoms are routinely encountered in nature.
c) Atoms may be decomposed using chemical change.
d) Two kinds of atoms may be present in a homoatomic molecule.
20. The total number of atoms present in one formula unit of Ca3(PO4)2 is
a) 13
b) 15
c) 16
d) 21
Long Answer:
Make sure to read the following questions carefully. To receive FULL credit,
1) Show your work
2) Provide your answers with the correct number of significant figures & units
3) Circle your answer
21. Round each of the following numbers to 3 significant figures.
118.521
__________________
99,140,210
0.00093105
__________________
2,010
__________________
__________________
22. Express the following exponential expressions in CORRECT scientific notation.
430 x 10-2
__________________
13.30 x 108
0.000330 x 10-2
__________________
0.123 x 106
__________________
__________________
23. Determine the number of significant figures in each of the following measurements.
3700 + 1
__________________
1.562 + 0.001
__________________
72,000 + 10
__________________
300 + 100
__________________
24. Perform the following conversions.
6.40 x 10-7 km3 to cm3
25. Density is an easy way to distinguish between gold (approx. density = 19 g/cm3) from fool’s gold (approx. density
= 4.5 g/cm3). If a large golden rock has a mass of 1083 g and a volume of 5.7 x 10-2L, is it real gold or fool’s
gold?
26. What is the capacity of a gasoline container, in gallons, if it will hold 123 pounds of gasoline? The density of
gasoline is 0.60 g/mL.
27. What is the density of lithium in lbs/ft3? (d = 0.53 g/ cm3)
28. How many electrons are present in 1 molecule of acetone, C3H6O?
29.How many electrons are present in 10 molecules of acetone, C3H6O?
30.The density of copper is 8.93 g/cm3, and the mass of a single copper atom is 1.06 x 10-22g. How many copper
atoms are present in a copper bar whose dimensions are 2.00 cm x 3.00 cm x 5.00 cm?
32. The natural distribution of the isotopes of chlorine is 75.8% 35Cl at 34.9689 amu and 24.2% 37Cl at 36.9659 amu.
Calculate the atomic mass of chlorine.