CHEM 101 Fall 10 Make-Up Exam (a)
On the answer sheet (scantron) write your name, student ID number, and recitation section
number. Choose the best (most correct) answer for each question and enter it on your answer
sheet.
Potentially useful data:
R = 0.08206 L·atm·mol-1·K-1
1 atm = 760 Torr = 760 mm Hg
Avogadro’s constant: 6.022 x 1023 mol-1
1. Please choose the letter “a” as your answer for this question.
2. To convert from one resonance structure to another,
a. only atoms can be moved.
b. electrons and atoms can both be moved.
c. only electrons can be moved.
d. neither electrons nor atoms can be moved.
e. electrons must be added.
3. Construct correct Lewis dot structures for the three molecules below. Determine which compounds, if
any, exceed the octet rule.
PF3
SF4
O3
I
II
III
a.
b.
c.
d.
e.
I
II
III
II and III
I, II, and III
4. Write the correct Lewis structure for XeF4. This molecule exceeds the octet rule. Determine the number
of bonding pairs and lone pairs on the central atom.
a. 4 bonding pairs and 1 lone pair
b. 5 bonding pairs and 0 lone pairs
c. 4 bonding pairs and 2 lone pairs
d. 5 bonding pairs and 2 lone pairs
e. 6 bonding pairs and 0 lone pairs
5. VSEPR is based upon what principle?
a. The size of the electrons in the valence shell of a molecule determines the shape of the
molecule.
b. The velocity of the electrons in the valence shell of a molecule determines the shape of the
molecule.
c. The repulsion of electrons in the valence shell of a molecule determines the shape of the
molecule.
d. The attraction of electrons in the valence shell of a molecule determines the shape of the
molecule.
e. The mass of the electrons in the valence shell of a molecule determines the shape of the
molecule.
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6. A Lewis diagram is shown below for the SO2 molecule. It shows three bonding pairs and a lone
pair at sulfur.
..
S
O
O
The VSEPR account of this molecule’s structure is based on:
a. two regions (domains) of electron density about the central atom.
b. three regions (domains) of electron density about the central atom.
c. three and a half regions (domains) of electron density about the central atom.
d. four regions (domains) of electron density about the central atom.
e. five regions (domains) of electron density about the central atom.
7. How many lone pairs of electrons does the Lewis dot structure of H2S have around its central atom and
what is the shape of the molecule?
a. 0, linear
b. 0, bent
c. 1, triangular planar
d. 2, tetrahedral
e. 2, bent
8. In VSEPR Theory, under which of the following conditions will the electron-pair geometry be the same
as the molecular geometry?
a. in molecules with at least one lone pair of electrons on the central atom
b. in molecules with no lone pairs of electrons on the substituent atoms
c. in molecules with a central atom which is a nonmetal
d. in molecules with no lone pairs of electrons on the central atom
e. in molecules with more than one octet around the central atom
9. Using VSEPR Theory, predict the electron-pair geometry of IF2−.
a. linear
b. bent (or angular)
c. triangular (or trigonal) bipyramidal
d. tetrahedral
e. T-shaped
10. Using VSEPR Theory, predict the electron-pair geometry and the molecular geometry of CO2.
a. tetrahedral, linear
b. tetrahedral, tetrahedral
c. linear, bent
d. bent, linear
e. linear, linear
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11. Using VSEPR Theory, predict the X-A-X angles for the following compounds:
CO2
GeF4
BCl3
a.
b.
c.
d.
e.
109.5°, 109.5°, 109.5°
109.5°, 90°, 90°
109.5°, 90°, 109.5°
180°, 109.5°, 120°
180°, 90°, 120°
12. Which of the following accurately describes a molecule with all polar covalent bonds?
a. It is always a polar molecule.
b. It is never a polar molecule.
c. It may be a polar molecule.
d. It may be an ionic molecule.
e. It cannot be a nonpolar molecule.
13. List whether the following molecules are polar or nonpolar.
CH2Cl2 ICl3 CO2
a.
b.
c.
d.
e.
nonpolar, nonpolar, nonpolar
nonpolar, nonpolar, polar
polar, nonpolar, polar
polar, polar, nonpolar
polar, polar, polar
14. Which molecule below has only London (or dispersion) intermolecular forces?
a. HF
b. OF2
c. PF3
d. CCl4
e. CH3Cl
15. Which of the following interactions are present between CH3COCH3 molecules?
I.
London (or dispersion) forces
II.
hydrogen bonding
III.
dipole-dipole attractions
a.
b.
c.
d.
e.
I only
I and III
II and III
III only
I, II, and III
16. What is the major type of force that must be overcome to allow the boiling of BF3?
a. ionic bonds
b. dipole-dipole attractions
c. hydrogen bonding
d. covalent bonds
e. London (or dispersion) forces
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17. Which concept is not associated with the kinetic-molecular theory of gases?
a. No energy is lost when gas molecules collide with each other.
b. The sizes of gas molecules are small compared to the distances between the molecules.
c. The average kinetic energy of gas molecules increases as the temperature increases.
d. The velocity of a gas molecule is inversely proportional to its temperature.
e. The forces of attraction and repulsion between separate gas molecules are minimal.
18. Which of the following correctly describes the relationship between the pressure of a gas and the volume
of a gas at constant temperature?
a. as one increases the other increases
b. unrelated
c. directly proportional
d. irreversibly proportional
e. inversely proportional
19. If a 2.0-liter sample of gas experiences a decrease in pressure from 1.74 atm to 0.555 atm at 25°C, what is
the resulting volume (in L) at 25°C?
a. 0.48 L
b. 0.64 L
c. 1.9 L
d. 6.3 L
e. 20 L
20. A 125.0-mL flask contains a gas at 27°C and 760 mm Hg of pressure. The gas is pumped into an empty
1.50-L flask also at a final temperature of 27°C. What is the pressure (in atm) of the gas in the new flask?
a. 8.33 × 10−2 atm
b. 6.33 × 101 atm
c. 8.33 × 101 atm
d. 6.33 × 104 atm
e. none of these choices
21. A sample of an ideal gas in a closed 3.00 L container at 25.0°C and 76.0 torr is heated to 300°C.
The pressure of the gas at this temperature is:
a. 912 torr.
b. 146 torr.
c. 76.5 torr.
d. 39.5 torr.
e. 2.53 × 10-2 torr.
22. What is the pressure (in atm) exerted by a 2.00 mole sample of gas that occupies 2.50 L at 34.0°C?
a. 40.3
b. 20.2
c. 80.7
d. 0.0496
e. 2.2
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23. If at 29°C a gas exerts 2.50 atm of pressure in a 5.99 L container, in what volume container (in L) would
the same gas exert 1.20 atm of pressure at 19°C?
a. 2.04 × 10−4
b. 6.04 × 10−1
c. 8.18
d. 12.1
e. 20.0
24. A 2.44 gram sample of an unknown gas is found to occupy a volume of 1.88 L at a pressure of
560 mm Hg and a temperature of 32°C. The molecular weight of the unknown gas is:
a. 32.
b.
c.
d.
e.
44.
28.
40.
20.
25. What is the temperature at which 11.7 g of N2 exerts 20.6 atm in a 500 mL volume?
a. 25.7°C
b. 299°C
c. 10.7°C
d. 8.05°C
e. 150°C
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chem101f10_exammakeupa
Answer Section
MULTIPLE CHOICE
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