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Name____________________________________________
Chem 105X
9-28-2011
Practice
Keller
Hour Exam I Chap Math,1-3 Kotz
Please take a seat in Row_____ Seat_____
according to the following map
Please:
 Keep this booklet closed until instructed to open it.

Turn off and remove from your person all electronic items including
PDAs, cell phones, earbuds, pagers, computers, progammable and
graphing calculators, and other similar devices. Place them in your
purse or pack on the floor or at the back of the room.

Place all papers, periodic tables, books, coats, packs, on the floor and
out of sight, or at the front or back of the room.

All you need are #2 pencils & a non-programmable calculator.
Exam Directions
 This is a closed book, 60-minute exam. Use nothing but the materials supplied to answer
the questions.
 There are a total of 8 pages in this exam, including the cover and back sheets.
 The attached back sheet contains reference information including constants and periodic
table.
 For questions 21 and 22, show your work, use the correct number of significant figures,
and include proper units in answer and in the work. Write legibly: if your answer
cannot be read by the grader, no credit can be given.
 Write YOUR NAME and fill in your STUDENT # on BUBBLE SHEET -- NOW.
 After you begin, write your NAME at the top of BOTH PAGE 6 and PAGE 7.
 WARNING; 5 pts may be deducted for incorrect or missing NAME or NUMBER.
Part I. Multiple Choice 4 POINTS EACH
Identify the letter of the choice that best completes the statement or answers the question. PUT YOUR ANSWER
ON THE ANSWER SHEET PROVIDED. Marks in this section of the exam booklet will not be graded.
____
1. Convert 0.490 ng to grams and express the answer in scientific notation using the correct number of
significant figures.
a. 4.90  10–8 g
b. 4.90  10–10 g
c. 4.9  10–10 g
d. 0.490  10–8 g
e. 0.490  10–10 g
____
2. What is the correct answer to the following expression: (86.11 – 85.49)  28.26? Carry out the
subtraction operation first.
a. 2  10–2
b. 2.2  10–2
c. 2.19  10–2
d. 2.194  10–2
e. 2.1939  10–2
____
3. Which of the following is the smallest volume?
a. 5.0  101 cm3
b. 0.50 dL
c. 0.50 mL
d. 5.0  103 uL
e. 5.0  10–2 L
____
4. Which one of the following is most likely to be a homogeneous mixture?
a. blood
b. ground beef
c. the air trapped inside an inflated balloon
d. chocolate chip cookies
e. mortar (a mixture of calcium carbonate and sand)
____
5. An electrically charged atom or group of atoms is a(n)
a. element.
b. ion.
c. chemical compound.
d. heterogeneous mixture.
e. homogeneous mixture.
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____
6. A cube of zirconium has a mass of 343 g. If each side of the cube has dimensions of 3.75 cm, what is
the density of zirconium?
a. 0.0410 g/cm3
b. 0.154 g/cm3
c. 6.50 g/cm3
d. 24.4 g/cm3
e. 18.1 g/cm3
____
7. All of the following are examples of chemical change EXCEPT
a. the condensation of steam.
b. the rusting of iron.
c. the combustion of gasoline.
d. the tarnishing of silver.
e. the decomposition of cinnabar (HgS) to mercury metal upon heating.
____
8. How many protons, neutrons, and electrons are in a yttrium-89 atom?
a. 39 protons, 50 neutrons, 39 electrons
b. 39 protons, 89 neutrons, 39 electrons
c. 39 protons, 50 neutrons, 50 electrons
d. 50 protons, 39 neutrons, 50 electrons
e. 39 protons, 11 neutrons, 39 electrons
____
9. Two isotopes of a given element will have the same number of ____, but a different number of ____ in
their nucleus.
a. protons, electrons
b. electrons, protons
c. protons, neutrons
d. neutrons, protons
e. electrons, neutrons
____ 10. Boron has two stable isotopes with masses of 10.01294 u and 11.00931 u. The average molar mass of
boron is 10.81 u. What is the percent abundance of each isotope?
a. 18.9% B-10 and 81.1% B-11
b. 20.0% B-10 and 80.0% B-11
c. 48.6% B-10 and 51.4% B-11
d. 80.0% B-10 and 20.0% B-11
e. 81.1% B-10 and 18.9% B-11
____ 11. A sulfide ion has ____ electrons.
a. 14
b. 15
c. 16
d. 17
e. 18
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____ 12. What is the correct formula for an ionic compound that contains barium ions and phosphate ions?
a. BaPO4
b. Ba3P2
c. Ba2(PO4)3
d. Ba(PO4)2
e. Ba3(PO4)2
____ 13. If 1.00 g of an unknown molecular compound contains 8.35  1021 molecules, what is its molar mass?
a. 44.0 g/mol
b. 66.4 g/mol
c. 72.1 g/mol
d. 98.1 g/mol
e. 132 g/mol
____ 14. The reaction of elemental chlorine with potassium iodide yields elemental iodine and potassium
chloride. Write a balanced chemical equation for this reaction.
a. Cl2(g) + KI(s)  I(s) + KCl2(s)
b. Cl2(g) + 2 KI(s)  I2(s) + 2 KCl(s)
c. Cl2(g) + KI2(s)  I2(s) + KCl2(s)
d. Cl(g) + KI(s)  I(s) + KCl(s)
e. Cl2(g) + 2 K2I(s)  I2(s) + 2 K2Cl(s)
____ 15. Which one of the following compounds is a nonelectrolyte (i.e. does not separate into ions) when
dissolved in water?
a. HCl
b. MgBr2
c. Cl2
d. Zn(NO3)2
e. KI
____ 16. A precipitate will form when aqueous Pb(NO3)2 is added to an aqueous solution of ____.
a. Cu(NO3)2
b. CaBr2
c. NaCH3CO2
d. Ca(ClO4)2
e. NaNO3
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____ 17. What is the net ionic equation for the reaction of aqueous calcium acetate and aqueous sodium
carbonate?
a. Ca2+(aq) + 2 CH3CO2–(aq)  Ca(CH3CO2)2(s)
b. Na+(aq) + CH3CO2–(aq)  NaCH3CO2(aq)
c. Na+(aq) + CH3CO2–(aq)  NaCH3CO2(s)
d. Ca2+(aq) + CO32–(aq)  CaCO3(s)
e. Ca2+(aq) + 2 Na+(aq)  CaNa2(s)
____ 18. What are the spectator ions in the reaction between aqueous hydrobromic acid and aqueous sodium
hydroxide?
a. Na+ only
b. H+ and OH–
c. Na+ and Br–
d. Br– only
e. H+, Br–, Na+, and OH–
____ 19. Write a balanced net ionic equation for the reaction of barium carbonate and aqueous hydrochloric
acid.
a. BaCO3(s) + 2 H+(aq)  Ba2+(aq) + CO32–(aq) + H2(g)
b. BaCO3(s) + 2 H+(aq)  Ba2+(aq) + CO2(g) + H2O( )
c. BaCO3(s) + 2 HCl(aq)  BaCl2(aq) + H2CO3(aq)
d. BaCO3(s) + 2 H+(aq)  Ba2+(aq) + H2CO3(s)
e. BaCO3(s) + 2 H+(aq)  BaO(s) + CO2(g) + H2(g)
____ 20. Write a balanced chemical equation for the reaction of aqueous solutions of potassium sulfide
and nitric acid.
a. K2S(aq) + 2 HNO3(aq)  2 KH(aq) + S(NO3)2(g)
b.
c.
d.
e.
K2S(aq) + HNO3(aq)  HS(g) + K2NO3(aq)
K2S(aq) + 2 HNO3(aq)  S(s) + H2(g) + 2 KNO3(aq)
K2S(aq) + 2 HNO3(aq)  2 K(s) + H2(g) + S(NO3)2(g)
K2S(aq) + 2 HNO3(aq)  H2S(g) + 2 KNO3(aq)
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Name_____________________________________
Part II. 10 points per question
For full credit, you must include units in all conversion factors and the final answer; use the correct
number of significant figures; and round off correctly. WRITE CLEARLY: if the grader cannot read
your writing, no credit will be assigned. If you need atomic weights, USE THE ATTACHED
PERIODIC TABLE, NOT THE TABLE ON THE WALL.
Question 21
The average Earth-Moon distance is 1.5 x 108 km. Calculate this distance in units of leagues.
(1 league = 3 miles; 1 m = 6.214 x 10-4 mile) SHOW YOUR WORK.
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Name_____________________________________
For full credit, you must include units in all conversion factors and the final answer; use the correct
number of significant figures; and round off correctly. WRITE CLEARLY: if the grader cannot read
your writing, no credit will be assigned.
Question 22
How many GRAMS of water contain 5.55 x 1021 hydrogen atoms? SHOW YOUR WORK.
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Avogadro’s number = 6.0221 x 1023 1 in = 2.54000 cm
1 amu = 1.661 x 10-24 g
1 mile = 5280.0 ft
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