100 Practice Questions for Chem 1C Midterm 1 - Joseph
1.
Which of the following statements is incorrect?
A) Ionic bonding results from the transfer of electrons from one atom to another.
B) Dipole moments result from the unequal distribution of electrons in a molecule.
C) The electrons in a polar bond are found nearer to the more electronegative element.
D) A molecule with very polar bonds can be nonpolar.
E)
Linear molecules cannot have a net dipole moment.
2.
Which of the following shows these molecules in order from most polar to least polar?
A) CH4 > CF2Cl2 > CF2H2 > CCl4 > CCl2H2
B) CH4 > CF2H2 > CF2Cl2 > CCl4 > CCl2H2
C) CF2Cl2 > CF2H2 > CCl2H2 > CH4 = CCl4
D) CF2H2 > CCl2H2 > CF2Cl2 > CH4 = CCl4
E)
CF2Cl2 > CF2H2 > CCl4 > CCl2H2 > CH4
3.
Which of the following is polar?
A) SiF4
B) XeF2
C) BCl3
D) NBr3
E)
SBr6
4.
Which statement is correct?
A) H2O is linear.
B) The molecule ClO2 cannot be accurately described by a Lewis structure consistent with the octet rule.
C) The diatomic molecule Cl2 is an example of a polar molecule.
D) The bonds in LiF have a more covalent character than those in F2.
E)
none of these
Use the following to answer question 5:
Consider the following molecules.
I. BF 3
II. CHBr3 (C is the central atom.)
III. Br 2
IV. XeCl 2
V. CO
VI. SF4
Select the molecule(s) that fit the given statement.
5.
A)
B)
C)
D)
E)
6.
These molecules have a zero net dipole moment.
III, V
I, III, IV
III, IV, V
I, III, IV, VI
none of them
Select the best Lewis structure for acetone, CH3COCH3.
H
H
C O C H
H
A)
H
B)
C
H
H
H
O
H
C
C
C H
H
H
H
C)
H C C O H C H
H
H
H
D)
H H C C O C H
H
H
H H H
H C C C O
H H
E)
7.
The Lewis structure for H3BO3 is
A)
H O B
O H
O
H
B)
H
O
B
O
H
O
H
O
H
C)
H
O
B
O
H
D)
H O
B
O
H
O
H
O
H
E)
H
O
B
O
H
8.
Which of the following is not a valid resonance structure for N3–?
N
N
N
N
N
N
N
N
N
N
N
N
-
A)
-
B)
-
C)
D)
E)
All are valid.
Use the following to answer question 9:
Draw the Lewis structures of the molecules below, and use them to answer the following questions.
I.
BH3
II. NO 2
III. SF 6
IV. O 3
V. PCl 5
9.
Which of these molecules show resonance?
A) I, II
B) II, IV
C) II, V
D) III, IV
E)
III, V
10.
Which of the following has an incomplete octet in its Lewis structure?
A) SO2
B) ICl
C) SF2
D) F2
E)
NO
11.
The molecule XCl5– has a square pyramidal shape. Which of the following atoms could be X?
A) O
B) P
C) Xe
D) S
E)
At least two of these atoms could be X.
12.
The Cl–Kr–Cl bond angle in KrCl4 is closest to
A) 90°.
B) 109°.
C) 120°.
D) 150°.
E)
360°
13.
Of the following, which molecule has the largest bond angle?
A) SO3
B) SF2
C) HCN
D) H2S
E)
PF3
14.
Select the correct molecular structure for SF4.
A) linear
B) bent
C) pyramidal
D) tetrahedral
E)
none of these
15.
Select the correct molecular structure for I3–.
A) linear
B) bent
C) pyramidal
D) tetrahedral
E)
none of these
E)
none of these
16.
How many of the following molecules and ions are linear?
NCl3
NH4+
SCNCO2
NO2A)
B)
C)
D)
E)
0
1
2
3
4
17.
What type of structure does the XeOF2 molecule have?
A) pyramidal
B) tetrahedral
C) T-shaped
D) trigonal planar
E)
octahedral
18.
Which ion is planar?
A) PF4+
B) CO32–
C) SO32–
D) ClO4–
E)
SCl5-
19.
Select the correct molecular structure for PO33–.
A) pyramidal
B) tetrahedral
C) square planar
D) octahedral
E)
none of these
20.
Which of the following molecules contains a nitrogen atom that is sp 2 hybridized?
A) NH3
B) NO3C) N2
D) HCN
E)
C2N2
21.
Consider the structure of glycine, the simplest amino acid:
H2N
H
O
C
C
OH
H
What is the total number of  bonds in the molecule?
A)
B)
C)
D)
E)
22.
0
1/2
1
2
More information is needed.
What is the hybridization of I in the molecule ICl3?
A) sp
B) sp2
C) sp3
D) dsp3
E)
d2sp3
23.
What is the hybridization of S in the molecule H2S?
A) sp
B) sp2
C) sp3
D) dsp3
E)
d2sp3
24.
What is the hybridization of C in the ion CN-?
A) sp
B) sp2
C) sp3
D) dsp3
E)
d2sp3
25.
Atoms that are sp3 hybridized form ____ pi bond(s).
A) 0
B) 1
C) 2
D) 3
E)
4
26.
What is the hybridization of the central atom in SF6?
A) sp
B) sp2
C) sp3
D) dsp3
E)
d2sp3
27.
What is the hybridization of the central atom in IF5?
A) sp
B) sp2
C) sp3
D) dsp3
E)
d2sp3
28.
What is the hybridization of the central atom in SF4?
A) sp
B) sp2
C) sp3
D) dsp3
E)
d2sp3
29.
Consider the following molecule. (Lone pairs are not drawn in.)
O
H2C CH C
1
2
3
CH2
4
C
N
5
Specify the hybridization of each carbon atom (in numeric order: C-1 C-2
A)
B)
C)
D)
E)
sp2
sp2
sp2
sp2
sp
sp2 sp2 sp3
sp2 sp2
sp3
2
3
sp
sp
sp3
ssp2 sp3 sp3
sp
sp
sp2
sp
sp3
sp
sp3
sp
C-3 C-4 C-5).
Use the following to answer questions 30-31:
Consider the following molecule. (Lone pairs are not drawn in.)
H
H
O
Cl
C
C
C
H
C
N
H
30.
What is the hybridization of the carbon atom that is double-bonded to oxygen?
A) sp
B) sp2
C) sp3
D) dsp3
E)
d2sp3
31.
What is the hybridization of the carbon atom that is bonded to chlorine?
A) sp
B) sp2
C) sp3
D) dsp3
E)
d2sp3
32.
Which of the following has two  bonds?
A) C2H6
B) C2H4
C) C2H2
D) at least two of these
E)
none of these
33.
Consider the following Lewis structure. (Lone pairs are not drawn in.)
H
H
O
H
H
C
C
C
C
3
2
1
H
H
Which statement about the molecule is false?
A)
B)
C)
D)
E)
There are 10 sigma and 2 pi bonds.
C-2 is sp2 hybridized with bond angles of 120.
Oxygen is sp3 hybridized.
This molecule contains 28 valence electrons.
There are some H–C–H bond angles of about 109 in the molecule.
Use the following to answer questions 34-36:
Tetracyanoethylene has the skeleton shown here:
From its Lewis structure, determine the following.
34.
How many sigma bonds and how many 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
35.
How many of the atoms are sp2 hybridized?
A) 2
B) 4
C) 6
D) 8
E)
10
36.
How many of the atoms are sp hybridized?
A) 2
B) 4
C) 6
D) 8
E)
10
37.
Which of the following has the shortest N-O bond?
A) NO3–
B) NO+
C) N2
D) NO2–
E)
none of these
38.
Complete the Lewis structure for the following molecule.
CH3 O
CH3 CH
C
C
N
This molecule has __________ sigma bonds and __________ pi bonds.
A)
B)
C)
D)
E)
4, 5
6, 3
11, 5
13, 2
13, 3
39.
Which of the following statements is correct?
A) A triple bond is composed of two  bonds and one  bond.
B)  bonds result from the head-to-head overlap of atomic orbitals.
C) Free rotation may occur about a double bond.
D)  bonds have electron density on the internuclear axis.
E)
More than one of these statements are correct.
40.
As the bond order of a bond increases, its bond energy ______ and its bond length ______.
A) increases, increases
B) decreases, decreases
C) increases, decreases
D) decreases, increases
41.
If four orbitals on one atom overlap four orbitals on a second atom, how many molecular orbitals will form?
A) 1
B) 4
C) 8
D) 16
E)
none of these
42.
For which of the following diatomic molecules would the bond order become greater if an electron were
removed, that is, if the molecule were converted to the positive ion in its ground state?
A) B2
B) C2
C) P2
D) F2
E)
Na2
43.
Which of the following species has the largest dissociation energy?
A) O2
B) O2–
C) O22–
D) O2+
E)
O22+
44.
Which of the following is paramagnetic?
A) B2
B) C2
C) H2
D) N2
E)
F2
45.
Order the following from shortest to longest bond: C2, B2, H2, N2
A) H2, N2, C2, B2
B) N2, C2, B2, H2
C) C2, N2, H2, B2
D) C2, B2, H2, N2
E)
none of these
46.
Which of the following statements is true?
A) Electrons are never found in an antibonding MO.
B) All antibonding MOs are higher in energy than the atomic orbitals of which they are composed.
C) Antibonding MOs have electron density mainly outside the space between the two nuclei.
D) None of these statements is true.
E)
Two of these statements are true.
47.
Which of the following is paramagnetic?
A) O2–
B) O2+
C) O2
D) N2
E)
At least two of these are paramagnetic.
48.
How many electrons are involved in pi bonding in benzene, C6H6?
A) 12
B) 30
C) 3
D) 6
E)
18
49.
Which of the following statements about the CO 32– ion is false?
A) The orbitals on the carbon atom are sp2 hybridized.
B) The ion is expected to be diamagnetic.
C) One C–O bond is shorter than the others.
D) The ion has a total of 24 electrons.
E)
It has a planar molecular geometry.
50.
Which of the following should have the highest boiling point?
A) Na2O
B) HF
C) NH3
D) N2
E)
H2O
51.
Identify the major attractive force in HF.
A) London dispersion forces
B) dipole-dipole interactions
C) hydrogen bonding
D) ionic bonding
E)
none of these
52.
Identify the major attractive force in H2S.
A) London dispersion forces
B) dipole-dipole interactions
C) hydrogen bonding
D) ionic bonding
E)
none of these
53.
Identify the major attractive force in CaF2.
A) London dispersion forces
B) dipole-dipole interactions
C) hydrogen bonding
D) ionic bonding
E)
none of these
54.
Identify the major attractive force in Ne.
A) London dispersion forces
B) dipole-dipole interactions
C) hydrogen bonding
D) ionic bonding
E)
none of these
55.
Which of the following compounds has the lowest boiling point?
A) CH4
B) C2H6
C) C3H8
D) C4H10
E)
C5H12
56.
Which of the following compounds has the highest boiling point?
A) C2H6
B) CO
C) H2
D) N2
E)
Ne
57.
Which of the following compounds has the highest boiling point?
A) CH4
B) H2O
C) NF3
D) O2
E)
He
58.
Which substance involves no intermolecular forces except London dispersion forces?
A) K
B) H2S
C) NaF
D) H2
E)
HCl
59.
The elements of Group 5A, the nitrogen family, form compounds with hydrogen that have the boiling points
listed below.
SbH3 –17°C, AsH3 –55°C, PH3 –87°C, NH3 –33°C
The first three elements illustrate a trend where the boiling point decreases as the mass decreases; however,
ammonia (NH3) does not follow the trend because of
A)
B)
C)
D)
E)
dipole-dipole attraction.
metallic bonding.
hydrogen bonding.
London dispersion forces.
ionic bonding.
60.
The resistance of a liquid to an increase in its surface area is called
A) capillary action.
B) surface tension.
C) vapor pressure
D) viscosity.
E)
none of these
61.
On the basis of your knowledge of bonding in liquids and solids, which of the following substances has the
highest melting temperature?
A) NaBr
B) Br2
C) NO2
D) CF4
E)
H2O
62.
Which of the following is the correct order of boiling points for NaNO 3, CH3OH, C2H6, and Ne?
A) Ne < CH3OH < C2H6 < NaNO3
B) NaNO3 < CH3OH < C2H6 < Ne
C) Ne < C2H6 < NaNO3 < CH3OH
D) Ne < C2H6 < CH3OH < NaNO3
E)
C2H6 < Ne < CH3OH < NaNO3
63.
In cubic closest-packed solids, what percentage of space is occupied by the spheres?
A) 43.8%
B) 52.4%
C) 68.0%
D) 74.0%
E)
none of these
64.
Which of the following is the smallest hole in a closest-packed lattice of spheres?
A) trigonal
B) tetrahedral
C) cubic
D) octahedral
E)
none of these
65.
Which substance can be described as cations bonded together by mobile electrons?
A) Ag(s)
B) S8(s)
C) Kr(l)
D) KCl(s)
E)
HCl(l)
66.
What is the net number of face-centered atoms contained in a face-centered cubic unit cell?
A) 1
B) 3
C) 4
D) 6
E)
none of these
Use the following to answer questions 67-69:
The molar volume of a certain form of solid lead is 18 cm 3/mol. Assuming cubic closest-packed structure,
determine the following.
67.
The number of Pb atoms per unit cell
A) 3
B) 4
C) 10
D) 12
E)
14
68.
The volume of a single cell
A) 1.20  102 pm3
B) 1.20  104 pm3
C) 1.20  106 pm3
D) 1.20  108 pm3
E)
none of these
69.
The radius of a Pb atom
A) 1.74 pm
B) 17.4 pm
C) 174 pm
D) 1740 pm
E)
none of these
70.
Which one of the following statements about solid Cu (face-centered cubic unit cell) is incorrect?
A) It will conduct electricity.
B) There are two atoms per unit cell.
C) The number of atoms surrounding each Cu atom is 12.
D) The solid has a cubic closest-packed structure.
E)
The length of a face diagonal is four times the Cu radius.
71.
Which of the following statements is(are) false?
I.
The hexagonal closest-packed structure is ABAB....
II. A body-centered cubic unit cell has four atoms per unit cell.
III. For unit cells having the same edge length, a simple cubic structure would have a smaller
density than a body-centered cube.
IV. Atoms in a solid consisting of only one element would have six nearest neighbors if the
crystal structure was a simple cubic array.
A)
B)
C)
D)
E)
72.
I only
II only
II, III only
I, IV
II, III, IV
Aluminum metal crystallizes in a face-centered cubic structure. What is the relationship between the radius of
an Al atom (r) and the length of an edge of the unit cell (E)?
A) r = E/2
r  E/ 8
B)
C)
D)
E)
r  ( 3 / 4) E
r = 2E
r = 4E
73.
A metal crystallizes in a body-centered unit cell with an edge length of 2.12  102 pm. Assume the atoms in
the cell touch along the cube diagonal. What will be the percentage of empty volume in the unit cell?
A) 0.00%
B) 26.0%
C) 32.0%
D) 68.0%
E)
75.5%
74.
A metal crystallizes with a face-centered cubic lattice. The edge of the unit cell is 434 pm. What is the
diameter of the metal atom?
A) 376 pm
B) 217 pm
C) 307 pm
D) 434 pm
E)
614 pm
75.
Chromium metal crystallizes as a body-centered cubic lattice. If the atomic radius of Cr is 1.25 angstroms,
what is the density of Cr metal in grams per cubic centimeter?
A) 5.52 g/cm3
B) 7.18 g/cm3
C) 7.81 g/cm3
D) 2.76 g/cm3
E)
3.59 g/cm3
76.
You are given a small bar of an unknown metal, X. You find the density of the metal to be 10.5 g/cm 3. An Xray diffraction experiment measures the edge of the unit cell as 409 pm. Assuming that the metal crystallizes
in a face-centered cubic lattice, what is X most likely to be?
A) Ag
B) Rh
C) Pt
D) Pb
E)
none of these
77.
A certain solid substance that is very hard, has a high melting point, and is nonconducting unless melted is
most likely to be
A) I2
B) KCl
C) NO2
D) H2O
E)
Cr
78.
The unit cell in a certain lattice consists of a cube formed by an anion at each corner, an anion in the center,
and a cation at the center of each face. The unit cell contains a net
A) 5 anions and 6 cations.
B) 5 anions and 3 cations.
C) 2 anions and 3 cations.
D) 3 anions and 4 cations.
E)
2 anions and 2 cations.
79.
A certain metal fluoride crystallizes in such a way that the fluoride ions occupy simple cubic lattice sites,
while the metal atoms occupy the body centers of half the cubes. What is the formula for the metal fluoride?
A) MF2
B) M2F
C) MF
D) MF8
E)
none of these
80.
Sodium oxide (Na2O) crystallizes in a structure in which the O2– ions are in a face-centered cubic lattice and
the Na+ ions are in tetrahedral holes. What is the number of Na + ions in the unit cell?
A) 2
B) 4
C) 6
D) 8
E)
none of these
81.
In the unit cell of sphalerite, Zn2+ ions occupy half the tetrahedral holes in a face-centered cubic lattice of S2–
ions. What is the number of formula units of ZnS in the unit cell?
A) 5
B) 4
C) 3
D) 2
E)
1
82.
A p-type semiconductor
A) is made by doping host atoms with atoms having more valence electrons than the host.
B) is made by doping host atoms with atoms having fewer valence electrons than the host.
C) has electrons that lie close in energy to the conduction bands.
D) two of these
E)
none of these
83.
Which of the compounds below is an example of a network solid?
A) S8(s)
B) SiO2(s)
C) MgO(s)
D) NaCl(s)
E)
C25H52(s)
84.
Which of the following statements is true about p-type silicon?
A) It is produced by doping Si with P or As.
B) Electrons are the mobile charge carriers.
C) It does not conduct electricity as well as pure Si.
D) All are true.
E)
None is true.
85.
Doping Se with As would produce a(n) __________ semiconductor with __________ conductivity compared
to pure Se.
A) n-type, increased
B) n-type, decreased
C) p-type, increased
D) p-type, decreased
E)
intrinsic, identical
86.
What is the vapor pressure of water at 100.0°C?
A) 85 torr
B) 760 torr
C) 175 torr
D) 1 torr
E)
More information is needed.
87.
Which of the following processes must exist in equilibrium with the condensation process when a
measurement of vapor pressure is made?
A) fusion
B) evaporation
C) sublimation
D) boiling
E)
none of these
88.
Given below are the temperatures at which two different liquid compounds with the same empirical formula
have a vapor pressure of 400 torr.
Compound
T (°C)
dimethyl ether, CH 3-O-CH3
-37.8
ethanol, CH 3CH2OH
63.5
Which of the following statements is false?
A)
B)
C)
D)
E)
Increasing the temperature will increase the vapor pressure of both liquids.
Intermolecular attractive forces are stronger in (liquid) ethanol than in (liquid) dimethyl ether.
The normal boiling point of dimethyl ether will be higher than the normal boiling point of ethanol.
The reason why the temperature at which the vapor pressure is 400 torr is higher for ethanol (than for
dimethyl ether) is that there is strong hydrogen bonding in ethanol.
None of these statements is false.
89.
Knowing that Hvap for water is 40.7 kJ/mol, calculate Pvap of water at 37°C.
A) 6.90 torr
B) 12.4 torr
C) 18.7 torr
D) 25.4 torr
E)
52.6 torr
90.
Which of the following statements is true about the vapor pressures of methane (CH 4) and ammonia (NH3)?
A) The vapor pressure of ammonia is greater than the vapor pressure of methane because ammonia is polar
and methane is nonpolar.
B) The vapor pressure of ammonia is less than the vapor pressure of methane because ammonia is nonpolar
and methane is polar.
C) The vapor pressure of methane is greater than the vapor pressure of methane because methane has more
hydrogen bonding than ammonia.
D) The vapor pressure of ammonia is equal to the vapor pressure of methane.
E)
None of these statements is true.
91.
You are given the following boiling-point data:
water, H 2O
100° C
methanol, CH 3OH
64.96° C
ethanol, CH 3CH2OH
78.5° C
diethyl ether, CH3OH2–O–CH2CH3
34.5° C
ethylene glycol, HO–CH2–CH2–OH
198° C
Which one of these liquids would you expect to have the highest vapor pressure at room temperature?
A)
B)
C)
D)
E)
92.
water, H2O
methanol, CH3OH
ethanol, CH3CH2OH
diethyl ether, CH3OH2–O–CH2CH3
ethylene glycol, HO–CH2–CH2–OH
Given the graph below, what is the boiling point of carbon tetrachloride at standard pressure?
A)
B)
C)
D)
E)
60°C
34°C
98°C
77°C
The graph does not give this information.
93.
Shown below is a phase diagram for compound X. At 25°C and 1 atm, in what state will X exist?
A)
B)
C)
D)
E)
94.
A sample consisting of CO2(g) and CO2(s) at equilibrium at –78°C and 1 atm pressure is heated to –30°C, and
the pressure is increased to 8 atm. Based on the phase diagram below, what will happen?
A)
B)
C)
D)
E)
95.
solid.
liquid.
gas.
gas/liquid at equilibrium.
gas/solid at equilibrium.
At equilibrium, only CO2(g) will be present.
All the CO2 will be converted to CO2(l).
At equilibrium, CO2(g) and CO2(l) will be present.
The melting point of the CO2(s) will decrease.
none of these
Shown below is a phase diagram for compound X. How will the melting point of X change with increased
pressure?
A)
B)
C)
D)
E)
It will increase.
It will decrease.
It will remain the same.
There is not enough information given.
It will increase and then decrease.
96.
Based on the phase diagram shown below, which of the following statements are correct?
I. Sublimation occurs at a point in the transformation that falls along a straight line from point A to point F.
II. C and E represent points where the gas and liquid phases are in equilibrium.
III. Hvap can be measured at point B.
IV. Molecules at point D have a greater average kinetic energy than those at point F.
V. The temperature at point E is called the critical temperature of the compound.
A)
B)
C)
D)
E)
97.
Choose the correct statement about the diagram below.
A)
B)
C)
D)
E)
98.
II, V
I, III, IV
I, II, III
II, IV, V
I, II, IV
The diagram is qualitatively correct for water.
The diagram shows that the melting point of the solid increases with increasing pressure.
The diagram shows the triple point above 1 atm pressure.
The diagram could represent the phase diagram of CO2.
None of these statements is correct.
A certain substance, X, has a triple-point temperature of 20°C at a pressure of 2.0 atm. Which one of the
following statements cannot possibly be true?
A) X can exist as a liquid above 20°C.
B) X can exist as a solid above 20°C.
C) Liquid X can exist as a stable phase at 25°C, 1 atm.
D) Both liquid and solid X have the same vapor pressure at 20°C.
E)
All of these statements could be true.
99.
Given the phase diagram shown below, which of the following statements is false?
A)
B)
C)
D)
E)
The solid has a higher density than the liquid.
At some (constant) temperature, the gaseous substance can be compressed into a solid and then into a
liquid in this order.
When phase A is compressed at constant temperature at point X, no change is observed.
When heated at 1 atm, this substance will first melt and then boil.
None of these statements is false.
100. The density of the solid phase of a substance is 0.90 g/cm3 and the density of the liquid phase is 1.0 g/cm3. A
large increase in pressure will
A) lower the freezing point.
B) raise the freezing point.
C) lower the boiling point.
D) raise the triple point.
E)
lower the triple point.
Answer Key
1. E
11. D
21. C
31. C
41. C
51. C
61. A
71. B
81. B
91. D
2. D
12. A
22. D
32. C
42. D
52. B
62. D
72. B
82. B
92. D
3. D
13. C
23. C
33. C
43. E
53. D
63. D
73. C
83. B
93. B
4. B
14. E
24. A
34. D
44. A
54. A
64. A
74. C
84. E
94. B
5. B
15. A
25. A
35. A
45. A
55. A
65. A
75. B
85. C
95. A
6. B
16. C
26. E
36. D
46. E
56. A
66. B
76. A
86. B
96. E
7. D
17. C
27. E
37. B
47. E
57. B
67. B
77. B
87. B
97. B
8. A
18. B
28. D
38. E
48. D
58. D
68. D
78. C
88. C
98. C
9. B
19. A
29. A
39. B
49. C
59. C
69. C
79. A
89. E
99. A
10. E
20. B
30. B
40. C
50. A
60. B
70. B
80. D
90. E
100. A