AP Chemistry Practice Test #6
Chapter 8 and 9
1. Which of the following statements is incorrect?
a.
b.
c.
d.
e.
Ionic bonding results from the transfer of electrons from one atom to another.
Dipole moments result from the unequal distribution of electrons in a molecule.
The electrons in a polar bond are found nearer to the more electronegative element.
A molecule with very polar bonds can be nonpolar.
Linear molecules cannot have a net dipole moment.
2. Atoms with very similar electronegativity values are expected to form
a.
b.
c.
d.
e.
no bonds.
covalent bonds.
triple bonds.
ionic bonds.
none of these
3. For the elements Rb, F, and O, the order of increasing electronegativity is:
a.
b.
c.
d.
e.
Rb < F < O
Rb < O < F
O < F < Rb
F < Rb < O
None of these
4. In which case is the bond polarity incorrect?
a.
b.
c.
d.
e.
δ+ H-F δδ+ K-O δδ+ Mg-Hδδ+ Cl-I δδ+ Si-S δ-
5. The electron pair in a C-F bond could be considered
a. closer to C because carbon has a larger radius and thus exerts greater control over the
shared electron pair.
b. closer to F because fluorine has a higher electronegativity value than carbon.
c. closer to C because carbon has a lower electronegativity value than fluorine.
d. an inadequate model since the bond is ionic.
e. centrally located directly between the C and F.
6. What is the correct order of the following bonds in terms of decreasing polarity?
a.
b.
c.
d.
e.
N-Cl, P-Cl, As-Cl
P-Cl, N-Cl, As-Cl
As-Cl, N-Cl, P-Cl
P-Cl, As-Cl, N-Cl
As-Cl, P-Cl, N-Cl
7. How many of the following molecules possess dipole moments?
BH3, CH4, PCl5, H2O, H2
a.
b.
c.
d.
e.
1
2
3
4
5
8. Which of the following molecules (or ions) has a dipole moment?
a. CO2
b. CO32c. NH4+
d. PF3
e. two of them do
9. Choose the statement that best describes the PbCl4 molecule in the gas phase.
a.
b.
c.
d.
e.
The bond angles are all about 109o.
The molecule is polar.
The molecule has a dipole moment.
The bonds are nonpolar.
a, b, and c
10. When electrons in a molecule are not found between a pair of atoms but move throughout the
molecule, this is called
a.
b.
c.
d.
e.
ionic bonding.
covalent bonding.
polar covalent bonding.
delocalization of the electrons.
a dipole moment.
11. Choose the molecule with the strongest bond.
a.
b.
c.
d.
e.
HF
HCl
HBr
HI
All are equal.
12. As the number of bonds between two carbon atoms increases, which one of the following
decreases?
a.
b.
c.
d.
e.
number of electrons between the carbon atoms
bond energy
bond length
all of these
none of these
13. Using the following bond energies
Bond
Bond Energy (kJ/mol)
C≡C
839
C-H
413
O=O
495
C=O
799
O-H
467
estimate the heat of combustion for one mole of acetylene:
C2H2(g) + (5/2)O2(g) → 2CO2(g) + H2O(g)
a.
b.
c.
d.
e.
1228 kJ
-1228 kJ
-447 kJ
+447 kJ
+365 kJ
14. Which of the following species is best described by drawing resonance structures?
a.
b.
c.
d.
e.
PH3
NH4+
O3
SO3HCN
Use the following to answer questions 15-17:
Using the following electronegativity values
C
2.5
C
3.2
H
2.2
N
3.0
O
3.4
select from the following group the molecule that fits the given statement:
a)
CH3CHO
b)_
CO2
c)
CH3Cl
d)
C2H6
e)
none
15. This molecule contains a carbon atom with trigonal planar geometry.
(a)
16. This molecule is the most polar.
(a)
17. This molecule shows the smallest number of lone pairs in its Lewis structure.
(d)
18. As indicated by Lewis structures, which of the following would probably not exist as a stable
molecule?
a. CH3OH
b. CH2O
c. CH3O
d. C2H2
e. C3H4
19. Select the best Lewis structure for acetone, CH3COCH3. (b)
a.
H
H
H
C
C O C H
H
H
H
H
O
H
C
C
C H
H
b.
H
H
c.
H C C O H C H
H
H
H
H H C C O C H
H
H
H H H
e.
H C C C O
H H
d.
20. Which of the following is the correct order for molecules from most to least polar?
a.
b.
c.
d.
e.
CH4 > CF2Cl2 > CF2H2 > CCl4 > CCl2H2
CH4 > CF2H2 > CF2Cl2 > CCl4 > CCl2H2
CF2Cl2 > CF2H2 > CCl2H2 > CH4 = CCl4
CF2H2 > CCl2H2 > CF2Cl2 > CH4 = CCl4
CF2Cl2 > CF2H2 > CCl4 > CCl2H2 > CH4
21. Of the following, which molecule has the largest bond angle?
a.
b.
c.
d.
e.
O3
OF2
HCN
H2O
More than one of the above have equally large bond angles.
22. According to the VSEPR model, the arrangement of electron pairs around NH3 and CH4 are
a. different because in each case there are a different number of atoms around the central
atom.
b. different because in each case there are a different number of electron pairs around the
central atom.
c. the same because both nitrogen and carbon are both in the second period.
d. the same because in each case there are the same number of electron pairs around the
central atom.
e. different or the same, depending on the conditions leading to maximum repulsion.
23. Which of the following atoms cannot exceed the octet rule in a molecule?
a.
b.
c.
d.
e.
N
S
P
I
All of the atoms (a-d) can exceed the octet rule.
24. In the cyanide ion (CN-), the nitrogen has a formal charge of
a.
b.
c.
d.
e.
-2
-1
0
2
2
25. How many of the following molecules – SF2, SF4, SF6, SiO2- are polar?
a.
b.
c.
d.
e.
0
1
2
3
4
26. How many resonance structures can be drawn for the molecule O3?
a.
b.
c.
d.
e.
1
2
3
4
5
27. Choose the electron dot formula that most accurately describes the bonding in CS2. (Hint:
Consider formal charges.)
a)
S C S
C S S
b)
S
C
S
S
C
S
S
C
S
c)
d)
e)
28. In the Lewis structure for elemental nitrogen there is (are)
a.
b.
c.
d.
e.
a single bond between the nitrogens.
a double bond between the nitrogens.
a triple bond between the nitrogens.
three unpaired electrons.
none of the above
Use the following to answer questions 29-31:
Consider the compound crotonaldehyde, whose skeleton is
H
H
H
H
H C1 C 2 C 3 C 4 O
H
29. How many electrons must be shown in the Lewis structure of this molecule?
a.
b.
c.
d.
e.
12
18
24
28
32
30. How many nonbonding electrons appear in the Lewis structure of this molecule?
a.
b.
c.
d.
e.
2
4
6
8
10
31. Which carbon in this molecule has tetrahedral bonding?
a. 1
b. 2
c. 3
d. 4
e. all
32. The Lewis structure for H3BO3 is
a)
H
O
O
B
H
O
H
b)
H
O
B
O
H
O
H
O
H
O
H
O
H
c)
H
O
B
O
d)
H
O
H
B
O
H
e)
H
O
B
O
H
Use the following to answer questions 33-34:
Consider the following molecules.
I.
BF3
II.
CHBr3 (C is the central atom)
III.
Br2
IV.
XeCl2
V.
CO
VI.
SF4
Select the molecule(s) that fit the given statement.
33. These molecules violate the octet rule.
a.
b.
c.
d.
e.
I, II, IV
I, III, IV, VI
III, V, VI
I, IV, VI
I, II, IV, VI
34. These molecules have a zero net dipole moment.
a.
b.
c.
d.
e.
III, V
I, III, IV
II, IV, V
I, III, IV, VI
none of them
35. The geometry of AsCl5 is
a.
b.
c.
d.
e.
trigonal bipyramidal
square pyramidal
distorted tetrahedral
octahedral
none of these
36. How many of the following molecules or ions are linear?
NH3 NH4+ HCN CO2 NO2
a.
b.
c.
d.
e.
0
1
2
3
4
37. The bond angles about the carbon atoms in the formaldehyde molecule, H2C=O, are about:
a.
b.
c.
d.
e.
120o
60o
109o
180o
90o
38. Which of the following species has a trigonal bypyramid structure?
a.
b.
c.
d.
e.
NH3
IF5
I3PCl5
none of these
39. Which ion is planar?
a.
b.
c.
d.
e.
NH4+
CO32SO32ClO3all are planar
40. In the molecule XeF2, how many pairs of electrons surround Xe and what is the
molecular geometry?
a.
b.
c.
d.
e.
4, bent
4, pyramidal
5, linear
5, bent
6, linear
41. How many of the following molecules have all of their atoms in the same plane>
H2C=CH2
F2O H2CO NH3 CO2 BeCl2
a.
b.
c.
d.
e.
3
4
5
6
7
Use the following to answer questions 42-45:
For each of the following compounds:
a)
draw the Lewis structure
b)
give the shape of the molecule
c)
indicate the polarity of the molecule
42. AlF3
trigonal planar, nonpolar
43. NH3
trigonal pyramidal; polar
44. ICl4-
square planar; nonpolar
45. CBrI3
tetrahedral; polar
46. If a compound has a number of individual dipoles, then
I.
it is polar overall
II.
there is an electronegativity difference between the bonded atoms
III.
it is ionic
IV.
it doesn’t have resonance
a.
b.
c.
d.
e.
II only
II, IV
I, II, IV
I, III
All of the above statements are correct.
47. The hybridization of the phosphorus atom in the cation PH2+ is:
a.
b.
c.
d.
e.
sp2
sp3
dsp
sp
none of these
48. Which of the following statements is (are) incorrect?
I.
II.
III.
IV.
a.
b.
c.
d.
e.
The hybridization of boron in BF3 is sp2.
The molecule XeF4 is nonpolar.
The bond order of N2 is three.
The molecule HCN has two pi bonds and two sigma bonds.
All four statements are correct.
II is incorrect.
I and IV are incorrect.
II and III are incorrect.
II, III, and IV are incorrect.
49. The hybridization of the central atom in I3- is:
a.
b.
c.
d.
e.
sp
sp2
sp3
dsp3
d2sp3
50. Which of the following does not contain at least one pi bond?
a.
b.
c.
d.
e.
H2CO
CO2
C2H4
C3H8
All of the aboe (a-d) contain at least one pi bond.
51. Consider the following Lewis structure
H
H
O
H
H
C
C
C
C
3
2
1
H
H
Which statement about the molecule is false?
a. There are 10 sigma and 2 pi bonds.
b. C-2 is sp2 hybridized with bond angles of 120o.
c. Oxygen is sp3 hybridized.
d. This molecule contains 28 valence electrons.
e. There are some H-C-H bond angles of about 109o in the molecule.
52. Consider the following Lewis structure:
H
H
C
H
O
H
C
1
H
a.
b.
c.
d.
e.
O
sp3
sp
sp
sp2
sp
C
C
C
2
3
4
H
C-1
sp3
sp3
sp2
sp3
sp3
C-2
sp
sp
sp
sp2
sp2
C-4
sp2
sp
sp2
sp3
sp
53. The hybridization of Br in BrF3 is
a.
b.
c.
d.
e.
sp
sp2
sp3
dsp3
d2sp3
N
H
54. The hybridization of the central atom Al, in AlBr3 is
a.
b.
c.
d.
e.
sp
sp2
sp3
dsp3
d2sp3
Use the following to answer questions 55-57:
Tetracyanoethylene has the skeleton shown below:
From its Lewis structure determine the following:
55. How many sigma and pi bonds are in the molecule?
a. 5 sigma and 9 pi
b. 6 sigma and 8 pi
c. 9 sigma and 7 pi
d. 9 sigma and 9 pi
e. 5 sigma and 8 pi
56. How many of the atoms are sp2 hybridized?
a.
b.
c.
d.
e.
2
4
6
8
10
57. How many of the atoms of sp hybridized?
a.
b.
c.
d.
e.
2
4
6
8
10