Exam 1T Date ________________ class hour _______________
Dr. H. J. Plastas
MONTGOMERY COLLEGE
This is a practice exam. Set aside two hours and try your best to work
it as a closed book exam. You may use only a periodic chart as a reference.
Once you have completed the exam as a closed book exam, and learned how
adequate your study methods have been, open your text and do the best you
can to complete any problems that you were unsure of in the closed book
format. E-mail your answers (1a 2b 3c 4d etc.) to your instructors e-mail
address. Do NOT send your answers to the Forum.
____ 1. Which of the following branches of chemistry is most related
to compounds containing carbon.
a. analytical b. inorganic c. physical
d. geo e. organic
____ 2. What is the number of significant digits in the measured number
0.03070?
a. two b. three c. four
d. five e. six
____ 3. The answer to the following problem should be rounded off to
how many significant digits? All values represent measurements.
116.21 + 2.3 - 33.25 = ?
a. one b. two c. three
d. four e. five
____ 4. Which of the following represents an exact number relationship.
a. 453.6 g = 1 lb
b. 1.057 qt = 1 L
c. 39.37 in = 1 m
d. 5280 ft = 1 mile
e. 1300 bees in a beehive
____ 5. Which of the following terms refers to the reproducibility of
a measurement?
a. precision
b. accuracy
c. random error
d. significant digits
e. systematic error
____ 6. Calculate the answer to the proper number of significant digits.
Both numbers represent measurements.
(1.216 x 10-3) - (4.613 x 10-4) = ?
a. 7.547 x 10-4 b. 2.77 x 104
c. 7.547 x 101 d. 7.55 x 101
e. 7.6 x 10-1
____ 7. Convert 17.2 miles to meters.
a. 2.72 x 10-4 b. 2.77 x 104 c. 4.29 x 103
d. 1.92 x 102 e. 4.29 x 104
____ 8. Platinum (Pt) has a density of 21.45 grams per cubic centimeter.
Calculate the volume in centiliters of 55.5 g of platinum.
a. 0.259 cL b. 0.2587 cL c. 1190 cL
d. 0.386 cL e. .03865 cL
____ 9. Convert -66o C to Kelvins.
a. 239 b. 339 c. -86.8 d. 207 e. -83.8
____ 10. How many decagrams (dag) in one centigram (cg)?
a. 10-1 b. 101 c. 10-2 d. 102 e. 10-3
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____ 11. How many joules of energy are required to heat 3.0 g of water
from 17o C to 21o C?
a. 12 J b. 38 J c. 50 J d. 53 J e. 480 J
____ 12. Calculate the volume in cubic centimeters of a cylinder of
gold (density 19 g/mL) 17 cm high with a radius of 5.0 cm.
a. 1300 b. 1600 c. 1900 d. 4500 e. 6800
____ 13. A 1992 U.S. penny is made of zinc (Zn) and copper (Cu). If
the penny weighs 2.55 g and contains 2.49 g of Zn, what is the percent
by weight of Cu in the penny?
a. 2.35 b. 2.41 c. 9.76 d. 50.0 e. 97.6
____ 14. Convert 78 degrees Fahrenheit to degrees Celsius.
a. 17 b. 24 c. 26 d. 29 e. 31
____ 15. At a fixed temperature, which of the following always has an
indefinite shape and a fixed volume?
a. matter b. a molecule c. solid d. liquid e. gas
____ 16. Which of the following involves a chemical change?
a. boiling water b. slicing an apple
c. melting snow d. ink drying
e. rusting of iron
____ 17. A pure substance that cannot be broken down into simpler substances
by ordinary chemical means is a or an:
a. compound b. element c. homogeneous mixture
d. heterogeneous mixture e. solid
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____ 18. Which of the following symbols is matched with the wrong
name?
a. B-boron b. N - nitrogen c. Ag - silver
d. Na-sodium e. Co - copper
____ 19. Which of the following symbols is matched with the wrong
name?
a. Sn - tin b. Pb - lead c. Hg - mercury
d. P - potassium e. Au - gold
____ 20. Choose the incorrect statement.
a. Both elements and compounds are pure substances.
b. Compounds have variable compositions.
c. Compounds contains two or more elements.
d. Mixtures contain two or more pure substances.
e. Homogeneous mixtures look alike throughout.
____ 21. All atoms of a given element have:
a. the same mass.
b. the same number of protons.
c. the same number of neutrons.
d. different numbers of electrons.
e. different numbers of neutrons.
____ 22. Which of the following has the smallest mass.
a. electron b. proton c. neutron d. isotope
e. isobar
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____ 23. The number of neutrons, protons and electrons respectively
in one atom of fluorine having a mass number of 21 is:
a. 9n, 12p, 12e b. 9n, 21p, 9e
c. 12n, 9p, 12e d. 12n, 10p, 10e
e. 12n, 9p, 9e
____ 24. Suppose a new element (atomic number 116) was discovered consisting
of two isotopes. The lighter isotope is 61.000% abundant with an isotopic
mass of 301.00 amu. The heavier isotope has an isotopic mass of 304.00
amu. Calculate the atomic mass (atomic weight) of this new element.
a. 301.99 b. 302.09 c. 302.13
d. 302.17 e. 302.50
____ 25. The density of silver is 10.5 grams per cubic centimeter and
the average mass of a silver atom is 1.79 x 10-22 g. How many
atoms are present in 3.33 mL of silver?
a. 1.77 x 1021 b. 1.77 x 1022 c. 1.95 x 1023
d. 2.29 x 1023 e. 6.02 x 1023
____ 26. The total number of atoms present in one formula unit of (NH4)2Cr2O7
is:
a. 4 b. 14 c. 18 d. 19 e. none of these
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____ 27. The nucleus of an atom:
a. accounts for only a small amount of the total volume of an atom.
b. accounts for only a small amount of the total mass of an atom.
c. is neutral because it contains neutrons.
d. contains protons and electrons.
e. none of the above.
____ 28. All atoms of a given element must have the same:
a. number of nucleon.
b. number of neutrons.
c. number of electrons.
d. mass number.
e. isotopic mass.
____ 29. Which of the following is a mixture?
a. water b. iron c. dry ice d. sulfur e. air
_____ 30. In which of the following sequences of elements do each of
the elements have a one-letter symbol.
a. hydrogen, sulfur, beryllium
b. potassium, boron, carbon
c. nitrogen, aluminum, chlorine
d. uranium, fluorine, sodium
e. neon, zinc, nickel
_____ 31. An isotope contains 53 protons, 78 neutrons and 53 electrons.
The mass number and atomic number of this isotope are, respectively.
a. 53 and 78 b. 78 and 53 c. 106 and 78
d. 106 and 53 e. 131 and 53
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____ 32. How many electrons are present in 5 molecules of NO2?
a. 15 b. 22 c. 23 d. 75 e. 115
____ 33. The most abundant element in the universe is:
a. helium b. hydrogen c. oxygen d. silicon
e. carbon