91 Practice Problems for Chapter 16 – Chem 1C
1.
Which one of the following is the strongest intermolecular force experienced by noble gases?
A) London dispersion forces
B) dipole-dipole interactions
C) hydrogen bonding
D) ionic bonding
E)
polar covalent bonds
2.
Properties of liquids lie (closer to/further from) properties of a solid than to (or from) properties of a gas.
A) closer to B) further from
3.
Molecular complexity leads to lower viscosity.
A) True
B) False
4.
Which of the following is most likely to be a gas at room temperature?
A) K2S
B) C8H18
C)
MgF2
D)
F2 E) H2O
5.
Which of the following should have the highest boiling point?
A) Na2O
B) HF C) NH3 D) N2
E) H2O
6.
Which intermolecular force is the strongest?
A) dipole-dipole interactions
B) London dispersion forces
C) hydrogen bonding
D) ionic bonding
E)
polar covalent bonds
7.
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
8.
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
9.
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
10.
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
11.
Identify the major attractive force in Cl2.
A) London dispersion forces
B) dipole-dipole interactions
C) hydrogen bonding
D) ionic bonding
E)
none of these
12.
Which of the following compounds has the lowest boiling point?
A) CH4
B) C2H6
C) C3H8 D) C4H10
E)
C5H12
13.
Which of the following compounds has the highest boiling point?
A) C2H6
B) CO C) H2 D) N2 E) Ne
14.
Which of the following compounds has the highest boiling point?
A) CH4
B) H2O C) NF3
D) O2 E) He
15.
Which substance involves no intermolecular forces except London dispersion forces?
A) K
B) H2S C) NaF D) H2 E) HCl
16.
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) dipole-dipole attraction. B) metallic bonding. C) hydrogen bonding. D) London dispersion forces.
E) ionic bonding.
17.
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
18.
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
19.
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
20.
Which statement regarding water is true?
A) Energy must be given off in order to break down the crystal lattice of ice to a liquid.
B) Hydrogen bonds are stronger than covalent bonds.
C) Liquid water is less dense than solid water.
D) Only covalent bonds are broken when ice melts.
E)
All of these statements are false.
21.
The unit cell in this two-dimensional crystal contains __________ Xs and __________ Os.
A)
22.
1, 1 B) 2, 1 C) 1, 2 D) 4, 1 E) 1, 4
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
23.
Which of the following is the smallest hole in a closest-packed lattice of spheres?
A)
B)
C)
D)
E)
trigonal
tetrahedral
cubic
octahedral
none of these
24.
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)
25.
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 26-28:
The molar volume of a certain form of solid lead is 18 cm 3/mol. Assuming cubic closest-packed structure,
determine the following.
26.
The number of Pb atoms per unit cell
A) 3 B) 4 C) 10 D) 12 E) 14
27.
The volume of a single cell
A) 1.20  102 pm3 B)
28.
The radius of a Pb atom
A) 1.74 pm B) 17.4 pm
1.20  104 pm3 C)
C)
174 pm
1.20  106 pm3 D) 1.20  108 pm3 E) none of these
D)
1740 pm
E)
none of these
29.
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.
30.
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) I only
B) II only
C) II, III only
D) I, IV
E)
II, III, IV
31.
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
B)
r  E/ 8
C)
D)
E)
r  ( 3 / 4) E
r = 2E
r = 4E
32.
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%
33.
A sample of Co crystallizes in the hexagonal closest-packed (hcp) structure. Each atom in a layer is
surrounded by and touches 6 other Co atoms. If the distance between Co atom centers within each layer is 2.0
 102 pm, what is the distance between centers of nearest neighbors in adjacent layers?
A) 1.5  102 pm
B) 2.0  102 pm
C) 2.3  102 pm
D) 4.0  102 pm
E)
none of these
34.
Mn crystallizes in the same cubic unit cell as Cu. Assuming that the radius of Mn is 5.6% larger than the
radius of Cu and that the density of copper is 8.96 g/cm3, calculate the density of Mn.
A) 9.46 g/cm3
B) 8.48 g/cm3
C) 9.12 g/cm3
D) 7.67 g/cm3
E)
6.58 g/cm3
35.
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
36.
If equal, rigid spheres are arranged in a simple cubic lattice in the usual way (that is, in such a way that they
touch each other), what fraction of the corresponding solid will be empty space? [The volume of a sphere is
(4/3)r3, with  = 3.14.]
A) 0.52
B) 0.32
C) 0.68
D) 0.48
E)
none of these
37.
What is the radius of the largest sphere that can be placed at the center of a face-centered cubic unit cell of a
cubic closest-packed array of spheres if the spheres have diameters of 4.00  102 pm?
A) 83.0 pm
B) 41.5 pm
C) 2.0  102 pm
D) 4.0  102 pm
E)
none of these
38.
Elemental magnesium crystallizes in a face-centered cubic lattice. The density of magnesium is 1.738 g/cm3.
The unit cell length is 4.80  102 pm. What is the atomic radius of Mg?
A) 242 pm
B) 340 pm
C) 215 pm
D) 170 pm
E)
126 pm
39.
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
40.
Pure rubidium crystallizes in a body-centered cubic lattice; the edge length of the unit cell is 562 pm. What is
the density of rubidium in grams per cubic centimeter?
A)
2  85.5  6.02  (5.62)3  10-1 g/cm3
B)
4  6.02
g/cm3
10  (5.62)3
C)
2  85.5  10
g/cm3
6.02  (5.62)3
D)
4  85.5  10
g/cm3
6.02  (5.62)3
E)
5  85.5  10
g/cm3
6.02  (5.62)3
41.
Metallic calcium crystallizes in a face-centered cubic lattice. The volume of the unit cell is 1.73  108 pm3.
What is the density of calcium metal?
A) 0.769 g/cm3
B) 0.385 g/cm3
C) 9.27 g/cm3
D) 1.54 g/cm3
E)
55.8 g/cm3
42.
You are given a small bar of an unknown metal, X. You find the density of the metal to be 10.5 g/cm3. 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
43.
A certain compound with a molar mass of 128.0 g/mol crystallizes with the sodium chloride (rock salt)
structure. The length of an edge of the unit cell is 457 pm. What is the density of this compound?
A) 8.91 g/cm3
B) 2.23 g/cm3
C) 5.36 g/cm3
D) 1.34 g/cm3
E)
1.86 g/cm3
44.
Which of the following substances would you expect to have the lowest boiling point?
A) graphite
B) methane, CH4
C) sodium nitrate, NaNO3
D) ethylene glycol, C2H4(OH)2
E)
sodium
45.
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
46.
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)
C)
D)
E)
5 anions and 3 cations.
2 anions and 3 cations.
3 anions and 4 cations.
2 anions and 2 cations.
47.
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
48.
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
49.
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
50.
Cs crystallizes in a body-centered cubic arrangement. Assuming that the dimensions of the unit cell for Cs
and for CsCl are equivalent, determine the ratio of the density of Cs to the density of CsCl.
A) 0.789
B) 1.00
C) 1.58
D) 2.79
E)
none of these
51.
Alkali halides commonly have either the sodium chloride structure or the cesium chloride structure. The
molar mass of CsCl is 2.88 times the molar mass of NaCl, and the edge length of the unit cell for NaCl is 1.37
times the edge length of the CsCl unit cell. Determine the ratio of the density of CsCl to the density of NaCl.
A) 1.85
B) 0.984
C) 2.10
D) 1.02
E)
0.541
52.
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
53.
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)
54.
Brass is an example of
A) a superconductor.
B) a substitutional alloy.
C) an interstitial alloy.
D) a network solid.
E)
none of these
55.
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.
56.
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
57.
A material is made from Al, Ga, and As. The mole fractions of these elements are 0.25, 0.26, and 0.49,
respectively. This material would be
A) a metallic conductor because Al is present.
B) an insulator.
C) a p-type semiconductor.
D) an n-type semiconductor.
E)
none of these
58.
Which of the following statements is incorrect?
A) Molecular solids have high melting points.
B) The binding forces in a molecular solid include London dispersion forces.
C) Ionic solids have high melting points.
D) Ionic solids are insulators.
E)
All of these statements are correct.
59.
A crystal of NaCl is
A) soft, low-melting, and a good electrical conductor.
B) hard, high-melting, and a good electrical conductor.
C) soft, low-melting, and a poor electrical conductor.
D) hard, high-melting, and a poor electrical conductor.
E)
soft, high-melting, and a poor electrical conductor.
60.
A salt, MY, crystallizes in a body-centered cubic structure with a Y– anion at each cube corner and an M+
cation at the cube center. Assuming that the Y– anions touch each other and the M+ cation at the center, and
that the radius of Y– is 1.58  102 pm, what is the radius of M+?
A) 65.4 pm
B) 116 pm
C) 79.0 pm
D) 41.1 pm
E)
52.7 pm
61.
When 1.00 mol of a pure liquid is vaporized at a constant pressure of 1.00 atm and at its boiling point of 321.6
K, 30.58 kJ of energy (heat) is absorbed and the volume change is +25.04 L. What is E for this process? (1
L-atm = 101.3 J)
A) 33.12 kJ
B) –2.51  103 kJ
C) –28.04 kJ
D) –33.12 kJ
E)
28.04 kJ
62.
When 1.00 mol of a pure liquid is vaporized at a constant pressure of 1.06 atm and at its boiling point of 330.4
K, 33.36 kJ of energy (heat) is absorbed and the volume change is +26.60 L. What is H for this process? (1
L-atm = 101.3 J)
A) 30.50 kJ
B) –30.50 kJ
C) 36.22 kJ
D) 33.36 kJ
E)
–36.22 kJ
63.
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.
64.
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
65.
In which of the following processes is energy evolved as heat?
A) sublimation
B) crystallization
C) vaporization
D) melting
E)
none of these
66.
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.
67.
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
68.
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.
69.
The normal boiling point of liquid X is less than that of Y, which is less than that of Z. Which of the
following is the correct order of increasing vapor pressure of the three liquids at STP?
A) X, Y, Z
B) Z, Y, X
C) Y, X, Z
D) X, Z, Y
E)
Y, Z, X
70.
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)
water, H2O
methanol, CH3OH
ethanol, CH3CH2OH
diethyl ether, CH3OH2–O–CH2CH3
ethylene glycol, HO–CH2–CH2–OH
71.
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.
72.
A liquid placed in a closed container will evaporate until equilibrium is reached. At equilibrium, which of the
following statements is not true?
A) The partial pressure exerted by the vapor molecules is called the vapor pressure of the liquid.
B) Liquid molecules are still evaporating.
C) The number of vapor molecules remains essentially constant.
D) The boundary (meniscus) between the liquid and the vapor disappears.
E)
All of these statements are true.
73.
How much energy is needed to convert 58.4 grams of ice at 0.00°C to water at 56.0°C?
Specific heat of ice = 2.10 J/(g°C)
Specific heat of water = 4.18 J/(g°C)
Heat of fusion = 333 J/g
Heat of vaporization = 2258 J/g
A)
B)
C)
D)
E)
13.7 kJ
5.76 kJ
146 kJ
33.1 kJ
54.5 kJ
74.
What is the vapor pressure of water at 80°C?
A) 0.48 atm
B) 0.80 atm
C) 1.00 atm
D) 1.20 atm
E)
2.00 atm
75.
Hvap for water is 40.7 kJ/mol. Calculate the boiling point of water at 0.500 atm.
A) 50.0°C
B) 81.3°C
C) 98.6°C
D) 100.0°C
E)
none of these
76.
The heat of vaporization of a certain refrigerant is 149 J/g. Calculate the number of kilograms of refrigerant
that must be evaporated to freeze a tray of 18 one-ounce (1 oz = 28 g) ice cubes starting with the water at
13°C.
Heat capacity (water) = 4.184 J/g °C
Hfusion (water) = 333 J/g
A)
B)
C)
D)
E)
77.
0.18 kg
0.94 kg
1.2 kg
4.7 kg
1.3 kg
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)
solid.
liquid.
gas.
gas/liquid at equilibrium.
gas/solid at equilibrium.
78.
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)
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
79.
The triple point of a substance is
A) the point at which its solid, liquid, and vapor are all in equilibrium.
B) the point at which the vapor pressure of the solid is 1 atm.
C) the point at which the liquid starts to condense as the temperature of the vapor is lowered.
D) the point at which the density of the solid and the liquid are equal.
E)
none of these
80.
Below is a phase diagram for compound X. What is the normal boiling point of X is most likely to be?
A)
B)
C)
D)
E)
15° C
47° C
73° C
18° C
0° C
81.
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)
82.
It will increase.
It will decrease.
It will remain the same.
There is not enough information given.
It will increase and then decrease.
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)
II, V
I, III, IV
I, II, III
II, IV, V
I, II, IV
83.
Choose the correct statement about the diagram below.
A)
B)
C)
D)
E)
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.
84.
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.
85.
The triple point of iodine is at 90 torr and 115°C. This means that liquid I 2
A) is more dense than I2(s).
B) cannot exist above 115°C.
C) cannot exist at 1 atm pressure.
D) cannot have a vapor pressure less than 90 torr.
E)
can exist at pressure of 10 torr.
86.
The triple point of CO2 is at 5.2 atm and –57°C. Under atmospheric conditions present in a typical Boulder,
Colorado, laboratory (P = 630 torr, T = 23° C), solid CO2 will
A) remain solid.
B) boil.
C) melt.
D) sublime.
E)
none of these
87.
A certain substance has the phase diagram shown below. At which of the following values of T and P is the
substance a pure liquid?
A)
B)
C)
D)
E)
88.
T = 8°C, P = 1 atm
T = 10°C, P = 0.5 atm
T = 70°C, P = 1.2 atm
T = 80°C, P = 1 atm
T = 10°C, P = 1 atm
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.
89.
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.
90.
Shown below is a phase diagram for sulfur (not drawn to scale). Sulfur can exist in solid modifications,
rhombic and monoclinic, denoted by SR and SM, respectively. Which of the following statements is incorrect?
A)
B)
C)
D)
E)
91.
Below is a phase diagram for compound X. You wish to purify a sample of X that was collected at P = 1.0
atm and T = 100 by subliming it. In order to sublime the sample, you should
A)
B)
C)
D)
E)
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
This system has two triple points.
Under ordinary atmospheric conditions (at sea level), sulfur does not sublime.
At pressures close to 1 atm, rhombic sulfur can be in stable equilibrium with liquid sulfur.
At a given pressure, there is (at most) one temperature at which rhombic sulfur can exist in equilibrium
with monoclinic sulfur.
None of these statements is incorrect.
A
A
B
D
A
D
C
B
D
A
increase P to 1.5 atm and then increase T to 300 K.
increase T to 300 K, keeping P = 1.0 atm.
lower P to 0.5 atm and then increase T to 200 K.
increase T to 300 K and then lower P to 0.5 atm.
abandon the attempt to sublime X.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
A
A
B
B
D
C
B
A
D
E
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
A
D
A
A
B
B
D
C
B
B
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
B
C
B
E
C
D
A
D
B
C
41.
42.
43.
44.
45.
46.
47.
48.
49.
50.
D
A
A
B
B
C
A
D
B
C
51.
52.
53.
54.
55.
56.
57.
58.
59.
60.
A
B
B
B
E
C
C
A
D
B
61.
62.
63.
64.
65.
66.
67.
68.
69.
70.
E
D
B
B
B
C
E
E
B
D
71.
72.
73.
74.
75.
76.
77.
78.
79.
80.
D
D
D
A
B
E
B
B
A
B
81.
82.
83.
84.
85.
86.
87.
88.
89.
90.
A
E
B
C
D
D
C
A
A
C
91. C