Answer at the bottom of the page
11.1 Multiple-Choice Questions
1) Crystalline solids __________.
A) have their particles arranged randomly
B) have highly ordered structures
C) are usually very soft
D) exist only at high temperatures
E) exist only at very low temperatures
2) In liquids, the attractive intermolecular forces are __________.
A) very weak compared with kinetic energies of the molecules
B) strong enough to hold molecules relatively close together
C) strong enough to keep the molecules confined to vibrating about their fixed lattice points
D) not strong enough to keep molecules from moving past each other
E) strong enough to hold molecules relatively close together but not strong enough to keep molecules from moving past each other
3) As a solid element melts, the atoms become __________ and they have __________ attraction for one another.
A) more separated, more
B) more separated, less
C) closer together, more
D) closer together, less
E) larger, greater
4) As a gaseous element condenses, the atoms become __________ and they have __________ attraction for one another.
A) more separated, more
B) more separated, less
C) closer together, more
D) closer together, less
E) larger, greater
5) A gas is __________ and assumes __________ of its container whereas a liquid is __________ and assumes __________ of its container.
A) compressible, the volume and shape, not compressible, the shape of a portion
B) compressible, the shape, not compressible, the volume and shape
C) compressible, the volume and shape, compressible, the volume
D) condensed, the volume and shape, condensed, the volume and shape
E) condensed, the shape, compressible, the volume and shape
6) Together, liquids and solids constitute __________ phases of matter.
A) the compressible
B) the fluid
C) the condensed
D) all of the
E) the disordered
7) Which statement is true about liquids but not true about solids?
A) They flow and are highly ordered.
B) They are highly ordered and not compressible.
C) They flow and are compressible.
D) They assume both the volume and the shape of their containers.
E) They flow and are not compressible.
8) The strongest interparticle attractions exist between particles of a __________ and the weakest interparticle attractions exist between particles of a __________.
A) solid, liquid
B) solid, gas
C) liquid, gas
D) liquid, solid
E) gas, solid
9) Which one of the following exhibits dipole-dipole attraction between molecules?
A) XeF4
B) AsH3
C) CO2
D) BCl3
E) Cl2
10) Which one of the following exhibits dipole-dipole attraction between molecules?
A) PH3
B) CCl4
C) Br2
D) CO2
E) C10H22
11) Of the following substances, only __________ has London dispersion forces as its only intermolecular force.
A) CH3OH
B) NH3
C) H2S
D) CH4
E) HCl
12) Of the following substances, only __________ has London dispersion forces as its only intermolecular force.
A) H2O
B) CCl4
C) HF
D) CH3COOH
E) PH3
13) Of the following substances, only __________ has London dispersion forces as the only intermolecular force.
A) CH3OH
B) NH3
C) H2S
D) Kr
E) HCl
14) Which one of the following should have the lowest boiling point?
A) PH3
B) H2S
C) HCl
D) SiH4
E) H2O
15) Which one of the following should have the lowest boiling point?
A) CH3OH
B) H2S
C) NH3
D) HCl
E) CH4
16) Of the following substances, __________ has the highest boiling point.
A) H2O
B) CO2
C) CH4
D) Kr
E) NH3
17) Of the following substances, __________ has the highest boiling point.
A) CH3CH2OH
B) C2H6
C) N2
D) F2
E) HOCH2CH2OH
18) Of the following, __________ has the highest boiling point.
A) N2
B) Br2
C) H2
D) Cl2
E) O2
19) In which of the following molecules is hydrogen bonding likely to be the most significant component of the total intermolecular forces?
A) CH4
B) C5H11OH
C) C6H13NH2
D) CH3OH
E) CO2
20) Which of the following has dispersion forces as its only intermolecular force?
A) CH4
B) HCl
C) C6H13NH2
D) NaCl
E) CH3Cl
21) When NaCl dissolves in water, aqueous Na+ and Cl- ions result. The force of attraction that exists between Na+ and H2O is called a(n) __________ interaction.
A) dipole-dipole
B) ion-ion
C) hydrogen bonding
D) ion-dipole
E) London dispersion force
22) __________ are particularly polarizable.
A) Small nonpolar molecules
B) Small polar molecules
C) Large nonpolar molecules
D) Large polar molecules
E) Large molecules, regardless of their polarity,
23) The ease with which the charge distribution in a molecule can be distorted by an external electrical field is called the __________.
A) electronegativity
B) hydrogen bonding
C) polarizability
D) volatility
E) viscosity
24) Which one of the following derivatives of ethane has the highest boiling point?
A) C2Br6
B) C2F6
C) C2I6
D) C2Cl6
E) C2H6
25) What is the predominant intermolecular force in CBr4?
A) London-dispersion forces
B) ion-dipole attraction
C) ionic bonding
D) dipole-dipole attraction
E) hydrogen-bonding
26) What is the predominant intermolecular force in CH3CH2OH?
A) London-dispersion forces
B) ion-dipole attraction
C) ionic bonding
D) induced dipole-dipole attraction
E) hydrogen-bonding
27) The intermolecular force(s) responsible for the fact that CH4 has the lowest boiling point in the set CH4, SiH4, GeH4, SnH4 is/are __________.
A) hydrogen bonding
B) dipole-dipole interactions
C) London dispersion forces
D) mainly hydrogen bonding but also dipole-dipole interactions
E) mainly London-dispersion forces but also dipole-dipole interactions
28) Elemental iodine (I2) is a solid at room temperature. What is the major attractive force that exists among different I2 molecules in the solid?
A) London dispersion forces
B) dipole-dipole rejections
C) ionic-dipole interactions
D) covalent-ionic interactions
E) dipole-dipole attractions
29) Hydrogen bonding is a special case of __________.
A) London-dispersion forces
B) ion-dipole attraction
C) dipole-dipole attractions
D) ion-ion interactions
E) none of the above
30) Which one of the following substances will have hydrogen bonding as one of its intermolecular forces?
A)
B)
C)
D)
E)
31) Which one of the following substances will not have hydrogen bonding as one of its intermolecular forces?
A)
B)
C)
D)
E)
32) What intermolecular force is responsible for the fact that ice is less dense than liquid water?
A) London dispersion forces
B) dipole-dipole forces
C) ion-dipole forces
D) hydrogen bonding
E) ionic bonding
33) The predominant intermolecular force in (CH3)2NH is __________.
A) London dispersion forces
B) ion-dipole forces
C) ionic bonding
D) dipole-dipole forces
E) hydrogen bonding
34) The predominant intermolecular force in AsH3 is __________.
A) London dispersion forces
B) ion-dipole forces
C) ionic bonding
D) dipole-dipole forces
E) hydrogen bonding
35) C12H26 molecules are held together by __________.
A) ion-ion interactions
B) hydrogen bonding
C) ion-dipole interactions
D) dipole-dipole interactions
E) dispersion forces
36) Which of the following molecules has hydrogen bonding as its only intermolecular force?
A) HF
B) H2O
C) C6H13NH2
D) C5H11OH
E) None, all of the above exhibit dispersion forces.
37) Which of the following molecules has hydrogen bonding as its only intermolecular force?
A) NH3
B) H2O
C) C3H7OH
D) HOCH2CH2OH
E) None, all of the above exhibit dispersion forces.
38) What types of intermolecular forces exist between HI and H2S?
A) dipole-dipole and ion-dipole
B) dispersion forces, dipole-dipole, and ion-dipole
C) dispersion forces, hydrogen bonding, dipole-dipole, and ion-dipole
D) dispersion forces and dipole-dipole
E) dispersion forces, dipole-dipole, and ion-dipole
39) What type(s) of intermolecular forces exist between Br2 and CCl4?
A) dispersion forces
B) dispersion forces and ion-dipole
C) dispersion forces and dipole-dipole
D) dispersion forces, ion-dipole, and dipole-dipole
E) None. Since both are gases at room temperature, they do not interact with each other.
40) What type(s) of intermolecular forces exist between Cl2 and CO3-2?
A) dispersion forces
B) dispersion forces and ion-dipole
C) dispersion forces, ion-dipole, and induced dipole – induced dipole
D) dispersion forces and ion-induced dipole
E) dispersion forces, ion-dipole, dipole-dipole, and ion-induced dipole
41) What types of intermolecular forces exist between NH3 and CBr4?
A) dispersion forces and dipole-dipole forces
B) dispersion forces and dipole-induced dipole forces
C) dispersion forces and hydrogen bonds
D) dispersion forces, hydrogen bonds, and induced dipole-induced dipole forces
E) dispersion forces, hydrogen bonds, and dipole-induced dipole forces
42) What types of intermolecular forces exist between PH3 and N2?
A) dispersion forces and dipole-dipole forces
B) dispersion forces and dipole-induced dipole forces
C) dispersion forces and hydrogen bonds
D) dispersion forces, hydrogen bonds, and induced dipole-induced dipole forces
E) dispersion forces, hydrogen bonds, and dipole-induced dipole forces
43) __________ is the energy required to expand the surface area of a liquid by a unit amount of area.
A) Viscosity
B) Surface tension
C) Volatility
D) Meniscus
E) Capillary action
44) Which statements about viscosity are true?
(i) Viscosity increases as temperature decreases.
(ii) Viscosity increases as molecular weight increases.
(iii) Viscosity increases as intermolecular forces increase.
A) (i) only
B) (ii) and (iii)
C) (i) and (iii)
D) none
E) all
45) The shape of a liquid’s meniscus is determined by __________.
A) the viscosity of the liquid
B) the type of material the container is made of
C) the relative magnitudes of cohesive forces in the liquid and adhesive forces between the liquid and its container
D) the amount of hydrogen bonding in the liquid
E) the volume of the liquid
46) Viscosity is __________.
A) the ‘skin” on a liquid surface caused by intermolecular attraction
B) the resistance to flow
C) the same as density
D) inversely proportional to molar mass
E) unaffected by temperature
47) How high a liquid will rise up a narrow tube as a result of capillary action depends on __________.
A) the magnitudes of cohesive forces in the liquid and adhesive forces between the liquid and the tube, and gravity
B) gravity alone
C) only the magnitude of adhesive forces between the liquid and the tube
D) the viscosity of the liquid
E) only the magnitude of cohesive forces in the liquid
48) The property responsible for the “beading up” of water is __________.
A) density
B) viscosity
C) vapor pressure
D) surface tension
E) hydrogen bonding
49) Heat of sublimation can be approximated by adding together __________ and __________.
A) heat of fusion, heat of condensation
B) heat of fusion, heat of vaporization
C) heat of freezing (solidification), heat of condensation
D) heat of freezing (solidification), heat of vaporization
E) heat of deposition, heat of vaporization
50) Which of the following statements is false?
A) The absolute value of the heat of sublimation is equal to the absolute value of the heat of deposition.
B) The heat of sublimation is equal to the sum of the heat of vaporization and the heat of melting.
C) The heat of sublimation is equal to the sum of the heat of vaporization and the heat of freezing.
D) The absolute value of the heat of sublimation is equal to the absolute value of the sum of the heat of condensation and the heat of freezing.
E) The absolute value of the heat of deposition is equal to sum of the absolute value of the heat of vaporization and the absolute value of the heat of freezing.
51) The phase changes B → C and D → E are not associated with temperature increases because the heat energy is used up to __________.
A) increase distances between molecules
B) break intramolecular bonds
C) rearrange atoms within molecules
D) increase the velocity of molecules
E) increase the density of the sample
52) Based on the following information, which compound has the strongest intermolecular forces?
Substance ΔHvap(kJ/mol)
Argon (Ar) 6.3
Benzene (C6H6) 31.0
Ethanol (C2H5OH) 39.3
Water (H2O) 40.8
Methane (CH4) 9.2
A) Argon
B) Benzene
C) Ethanol
D) Water
E) Methane
53) Which compound has the strongest intermolecular forces?
A) CBr4
B) C12H26
C) CI4
D) N2
E) O2
54) Large intermolecular forces in a substance are manifested by __________.
A) low vapor pressure
B) high boiling point
C) high heats of fusion and vaporization
D) high critical temperatures and pressures
E) all of the above
55) A substance that expands to fill its container yet has a density approaching that of a liquid, and that can behave as a solvent is called a(n) __________.
A) plasma
B) gas
C) liquid
D) amorphous solid
E) supercritical fluid and gas
56) The critical temperature and pressure of CS2 are 279°C and 78 atm, respectively. At temperatures above 279°C and pressures above 78 atm, CS2 can only occur as a __________.
A) solid
B) liquid
C) liquid and gas
D) gas
E) supercritical fluid
57) The substance with the largest heat of vaporization is __________.
A) I2
B) Br2
C) Cl2
D) F2
E) O2
58) Of the following, __________ is an exothermic process.
A) melting
B) subliming
C) freezing
D) boiling
E) All of the above are exothermic.
59) Of the following, __________ should have the highest critical temperature.
A) CBr4
B) CCl4
C) CF4
D) CH4
E) H2
60) Of the following, __________ is the most volatile.
A) CBr4
B) CCl4
C) CF4
D) CH4
E) C6H14
61) Of the following, __________ is the least volatile.
A) CBr4
B) CCl4
C) CF4
D) CH4
E) C6H14
62) A volatile liquid is one that __________.
A) is highly flammable
B) is highly viscous
C) is highly hydrogen-bonded
D) is highly cohesive
E) readily evaporates
63) In general, the vapor pressure of a substance increases as __________ increases.
A) surface tension
B) molecular weight
C) hydrogen bonding
D) viscosity
E) temperature
64) The vapor pressure of any substance at its normal boiling point is
A) 1 Pa
B) 1 torr
C) 1 atm
D) equal to atmospheric pressure
E) equal to the vapor pressure of water
65) Volatility and vapor pressure are __________.
A) inversely proportional to one another
B) directly proportional to one another
C) not related
D) the same thing
E) both independent of temperature
66) Some things take longer to cook at high altitudes than at low altitudes because __________.
A) water boils at a lower temperature at high altitude than at low altitude
B) water boils at a higher temperature at high altitude than at low altitude
C) heat isn’t conducted as well in low density air
D) natural gas flames don’t burn as hot at high altitudes
E) there is a higher moisture content in the air at high altitude
67) The vapor pressure of a liquid __________.
A) increases linearly with increasing temperature
B) increases nonlinearly with increasing temperature
C) decreases linearly with increasing temperature
D) decreases nonlinearly with increasing temperature
E) is totally unrelated to its molecular structure
68) The slope of a plot of the natural log of the vapor pressure of a substance versus 1/T is __________.
A) ΔHvap
B) -ΔHvap
C)
D)
E)
69) On a phase diagram, the critical pressure is __________.
A) the pressure required to melt a solid
B) the pressure below which a substance is a solid at all temperatures
C) the pressure above which a substance is a liquid at all temperatures
D) the pressure at which a liquid changes to a gas
E) the pressure required to liquefy a gas at its critical temperature
70) On a phase diagram, the critical temperature is __________.
A) the temperature below which a gas cannot be liquefied
B) the temperature above which a gas cannot be liquefied
C) the temperature at which all three states are in equilibrium
D) the temperature required to melt a solid
E) the temperature required to cause sublimation of a solid
71) On a phase diagram, the melting point is the same as __________.
A) the triple point
B) the critical point
C) the freezing point
D) the boiling point
E) the vapor-pressure curve
72) When the phase diagram for a substance has a solid-liquid phase boundary line that has a negative slope (leans to the left), the substance __________.
A) can go from solid to liquid, within a small temperature range, via the application of pressure
B) sublimes rather than melts under ordinary conditions
C) cannot go from solid to liquid by application of pressure at any temperature
D) cannot be liquefied above its triple point
E) melts rather than sublimes under ordinary conditions
73) The predominant intermolecular force in CaBr2 is __________.
A) London-dispersion forces
B) ion-dipole forces
C) ionic bonding
D) dipole-dipole forces
E) hydrogen bonding
74) Which of the following is most likely to exhibit liquid-crystalline behavior?
A) CH3CH2-C(CH3)2-CH2CH3
B) CH3CH2CH2CH2CH2CH2CH2CH3
C) CH3CH2CH2CH2CH2-Na+
D)
E)
75) Which of the following characteristics would prevent liquid crystal behavior?
A) long axial structure
B) ionic configuration
C) carbon-carbon single bonds
D) double bonding
E) polar groups
76) In the smectic A liquid-crystalline phase, __________.
A) the molecules are aligned along their long axes, with no ordering with respect to the ends of the molecules
B) the molecules are arranged in sheets, with their long axes parallel and their ends aligned as well
C) the molecules are aligned with their long axes tilted with respect to a line perpendicular to the plane in which the molecules are stacked
D) disk-shaped molecules are aligned through a stacking of the disks in layers
E) the molecules are oriented in a totally random fashion
77) In the __________ liquid crystalline phase, the component molecules exhibit only one dimensional ordering.
A) nematic
B) smectic A
C) smectic B
D) smectic C
E) cholesteric
78) In the ________ liquid crystalline phase, the component molecules are aligned along their long axis and are arranged in layers with the molecules in each plane twisted slightly in relation to the molecules in the planes above and below.
A) nematic
B) smectic A
C) smectic B
D) smectic C
E) cholesteric
79) Cholesteric liquid crystals are colored because __________.
A) each molecule is a chromophore
B) of the slight twist between layers
C) of the large spacing between layers
D) of the large number of conjugated bonds
E) all of the molecules contain multiple benzene rings
80) Molecules with only single bonds do not generally exhibit liquid-crystalline properties because __________.
A) molecules without multiple bonds lack the rigidity necessary for alignment
B) molecules without multiple bonds are too small to exhibit liquid-crystalline properties
C) molecules with only single bonds are gases
D) molecules with only single bonds are too big to exhibit liquid-crystalline properties
E) molecules without multiple bonds lack the flexibility necessary for alignment
81) For a given substance that exhibits liquid-crystalline properties, the transition from solid to liquid-crystal state occurs __________.
A) over a range of temperatures between the melting point of the solid and the boiling point of the liquid
B) at the melting point of the solid
C) over a range of temperatures that includes the melting point of the solid
D) at a well defined temperature above the melting point of the solid
E) at a well defined temperature below the melting point of the solid
82) For a given substance that exhibits liquid-crystalline properties, the liquid-crystalline state exists __________.
A) at one particular temperature below the melting point of the solid
B) in a range of temperatures below the melting point of the solid
C) at one particular temperature above the melting point of the solid
D) in a range of temperatures above the melting point of the solid
E) in a range of temperatures from below the melting point to above the melting point
11.2 Bimodal Questions
1) Based on molecular mass and dipole moment of the five compounds in the table below, which should have the highest boiling point?
A) CH3CH2CH3
B) CH3OCH3
C) CH3Cl
D) CH3CHO
E) CH3CN
2) The heating curve shown was generated by measuring the heat flow and temperature for a solid as it was heated. The slope of the __________ segment corresponds to the heat capacity of the liquid of the substance.
A) AB
B) BC
C) CD
D) DE
E) EF
3) The heating curve shown was generated by measuring the heat flow and temperature for a solid as it was heated. The slope of the __________ segment corresponds to the heat capacity of the solid.
A) AB
B) BC
C) CD
D) DE
E) EF
4) The heating curve shown was generated by measuring the heat flow and temperature for a solid as it was heated. The slope of the __________ segment corresponds to the heat capacity of the gas.
A) AB
B) BC
C) CD
D) DE
E) EF
5) The heating curve shown was generated by measuring the heat flow and temperature of a solid as it was heated. The heat flow into the sample in the segment __________ will yield the value of the ΔHvap of this substance.
A) AB
B) BC
C) CD
D) DE
E) EF
6) The heating curve shown was generated by measuring the heat flow and temperature of a solid as it was heated. The heat flow into the sample in the segment __________ will yield the value of the ΔHfusion of this substance.
A) AB
B) BC
C) CD
D) DE
E) EF
7) On the phase diagram shown above, segment __________ corresponds to the conditions of temperature and pressure under which the solid and the gas of the substance are in equilibrium.
A) AB
B) AC
C) AD
D) CD
E) BC
8) On the phase diagram shown above, the coordinates of point __________ correspond to the critical temperature and pressure.
A) A
B) B
C) C
D) D
E) E
9) On the phase diagram shown above, the coordinates of point __________ correspond to the triple point.
A) A
B) B
C) C
D) D
E) E
10) The phase diagram of a substance is given above. The region that corresponds to the solid phase is __________.
A) w
B) x
C) y
D) z
E) x and y
11) The normal boiling point of the substance with the phase diagram shown above is __________°C.
A) 10
B) 20
C) 30
D) 40
E) 50
12) The normal melting point of the substance with the phase diagram shown above is __________°C.
A) 15
B) 25
C) 35
D) 45
E) 55
13) The phase diagram of a substance is shown above. The area labeled __________ indicates the gas phase for the substance.
A) w
B) x
C) y
D) z
E) y and z
14) The phase diagram of a substance is shown above. The area labeled __________ indicates the solid phase for the substance.
A) w
B) x
C) y
D) z
E) y and z
15) The phase diagram of a substance is shown above. The area labeled __________ indicates the liquid phase for the substance.
A) w
B) x
C) y
D) z
E) y and z
16) According to the phase diagram shown above, the normal boiling point of this substance is __________°C.
A) -3
B) 10
C) 29
D) 38
E) 0
17) According to the phase diagram shown above, the normal melting point of this substance is __________°C.
A) -13
B) 10
C) 29
D) 38
E) 0
18) A __________ liquid crystal has the least order and is the most liquid-like.
A) nematic
B) smectic
C) cholesteric
D) smectic B
E) smectic C
19) Which type of liquid crystal is colored and changes color with temperature?
A) nematic
B) smectic A
C) cholesteric
D) smectic B
E) smectic C
11.3 Algorithmic Questions
1) The enthalpy change for converting 1.00 mol of ice at -50.0°C to water at 70.0°C is __________ kJ. The specific heats of ice, water, and steam are 2.09 J/g-K, 4.18 J/g-K, and 1.84 J/g-K, respectively. For H2O, ΔHfus = 6.01 kJ/mol, and ΔHvap = 40.67 kJ/mol
A) 12.28
B) 6.41
C) 13.16
D) 7154
E) 9.40
2) The enthalpy change for converting 10.0 g of ice at -25.0°C to water at 80.0°C is __________ kJ. The specific heats of ice, water, and steam are 2.09 J/g-K, 4.18 J/g-K, and 1.84 J/g-K, respectively.
For H2O, ΔHfus = 6.01 kJ/mol, and ΔHvap = 40.67 kJ/mol
A) 12.28
B) 6.16
C) 3870
D) 7.21
E) 9.88
3) The heat of fusion of water is 6.01 kJ/mol. The heat capacity of liquid water is 75.3 J/mol ∙ K. The conversion of 50.0 g of ice at 0.00°C to liquid water at 10.0°C requires __________ kJ of heat.
A) 2110
B) 18.8
C) 2.11
D) 16.7
E) Insufficient data are given.
4) Calculate the enthalpy change (in kJ) associated with the conversion of 25.0 grams of ice at -4.00°C to water vapor at 106.0°C. The specific heats of ice, water, and steam are 2.09 J/g-K, 4.18 J/g-K, and 1.84 J/g-K, respectively. For H2O, ΔHfus = 6.01 kJ/mol and ΔHvap = 40.67 kJ/mol.
A) 64.8
B) 75.8
C) 11000
D) 12000
E) 112
5) Ethanol (C2H5OH) melts at -114°C. The enthalpy of fusion is 5.02 kJ/mol. The specific heats of solid and liquid ethanol are 0.97 J/g-K and 2.3 J/g-K, respectively. How much heat (kJ) is needed to convert 25.0 g of solid ethanol at -135°C to liquid ethanol at -50°C?
A) 207.3
B) -12.7
C) 6.91
D) 4192
E) 9.21
6) Based on the figure above, the boiling point of diethyl ether under an external pressure of 1.32 atm is __________°C.
A) 10
B) 20
C) 30
D) 40
E) 0
7) Based on the figure above, the boiling point of ethyl alcohol under an external pressure of 0.0724 atm is __________°C.
A) 80
B) 60
C) 70
D) 40
E) 20
8) Based on the figure above, the boiling point of water under an external pressure of 0.493 atm is __________°C.
A) 80
B) 40
C) 60
D) 70
E) 90
9) The phase diagram of a substance is given above. This substance is a __________ at -10°C and 1.0 atm.
A) liquid
B) solid
C) gas
D) supercritical fluid
E) crystal
11.4 Short Answer Questions
1) In general, intramolecular forces determine the __________ properties of a substance and intermolecular forces determine its __________ properties.
2) London Dispersion Forces tend to __________ in strength with increasing molecular weight.
3) The direct conversion of a solid to a gas is called __________.
4) The initial discovery of a liquid crystal resulted from studies on what compound?
11.5 True/False Questions
1) The principal source of the difference in the normal boiling points of ICl (97°C; molecular mass 162 amu) and Br2 (59°C; molecular mass 160 amu) is both dipole-dipole interactions and London dispersion forces.
2) The boiling points of normal hydrocarbons are higher than those of branched hydrocarbons of similar molecular weight because the London-dispersion forces between normal hydrocarbons are greater than those between branched hydrocarbons.
3) Heats of vaporization are greater than heats of fusion.
4) Under ordinary conditions, a substance will sublime rather than melt if its triple point occurs at a pressure above atmospheric pressure.
5) Molecules containing only single bonds do not exhibit liquid-crystal behavior because free rotation can occur around single bonds making these molecules flexible.
Answer:
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