AP Chem Exam Review
(174).webp "AP Chem Exam Review - Quiz")
It’s another day, and that means it’s time for another examination on an Advanced Placement subject! Today we’ll be looking at one of the cornerstones of scientific study; Chemistry! How much do you know about the states of matter, for example? Find out in this AP Chem Exam Review!
Questions and Answers
- 1.
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
Correct Answer
E. Strong enough to hold molecules relatively close together but not strong enough to keep molecules from moving past each otherExplanation
The correct answer is "strong enough to hold molecules relatively close together but not strong enough to keep molecules from moving past each other." This explanation states that the attractive intermolecular forces in liquids are strong enough to keep the molecules close to each other, creating a relatively high density compared to gases. However, these forces are not strong enough to completely restrict the movement of molecules, allowing them to move past each other and flow freely.Rate this question:
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- 2.
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
Correct Answer
B. More separated, lessExplanation
When a solid element melts, the atoms gain enough energy to break their rigid structure and start moving more freely. As a result, they become more separated from each other. Additionally, as the atoms move further apart, the attractive forces between them weaken, leading to less attraction for one another. Therefore, the correct answer is "more separated, less."Rate this question:
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- 3.
Which statement is true about liquids?
- A.
They flow and are highly ordered.
- B.
They are highly ordered and not compressible.
- C.
They flow and are slightly compressible.
- D.
They assume both the volume and shape of their containers.
Correct Answer
C. They flow and are slightly compressible.Explanation
Liquids are characterized by their ability to flow, meaning they can easily change their shape and move from one place to another. This is why liquids can be poured or poured into containers. Additionally, liquids are slightly compressible, meaning their volume can be reduced under high pressure. While liquids do have some degree of order, they are not highly ordered like solids. Therefore, the statement "They flow and are slightly compressible" is true about liquids.Rate this question:
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- 4.
What is the predominant intermolecular force in AsH3?
- A.
London-dispersion forces
- B.
Ion-dipole attraction
- C.
Ionic bonding
- D.
Dipole-dipole attraction
- E.
Hydrogen bonding
Correct Answer
D. Dipole-dipole attractionExplanation
The predominant intermolecular force in AsH3 is dipole-dipole attraction. This is because AsH3 is a polar molecule, with the As atom being more electronegative than the H atoms. This creates a permanent dipole moment, with the As atom having a partial negative charge and the H atoms having partial positive charges. These dipoles attract each other, leading to dipole-dipole interactions between AsH3 molecules. London-dispersion forces and hydrogen bonding are not as significant in this molecule, while ion-dipole attraction and ionic bonding are not applicable in this case.Rate this question:
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- 5.
The principal source of the difference in the normal boiling points of ICl (97 degrees C; molecular mass 162 amu) and Br (59 degrees C; molecular mass 160 amu) is _________.
- A.
London dispersion forces
- B.
Dipole-dipole interactions
- C.
Hydrogen bonding
- D.
Both hydrogen bonding and dipole-dipole interactions
Correct Answer
B. Dipole-dipole interactionsExplanation
The principal source of the difference in the normal boiling points of ICl and Br is dipole-dipole interactions. Dipole-dipole interactions occur between polar molecules and are stronger than London dispersion forces, which are the primary intermolecular forces in nonpolar molecules. ICl is a polar molecule due to the difference in electronegativity between iodine and chlorine, while Br is a nonpolar molecule. Therefore, ICl experiences stronger dipole-dipole interactions, leading to a higher boiling point compared to Br.Rate this question:
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- 6.
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
Correct Answer
D. Ion-dipoleExplanation
When NaCl dissolves in water, the Na+ ions are attracted to the partially negative oxygen atoms in water molecules, while the Cl- ions are attracted to the partially positive hydrogen atoms in water molecules. This attraction between ions and water molecules is called an ion-dipole interaction.Rate this question:
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- 7.
Of the following substances, only _________ has London dispersion forces as its only intermolecular force.
- A.
CH3OH
- B.
NH
- C.
H2S
- D.
CH4
- E.
HCl
Correct Answer
D. CH4Explanation
The correct answer is CH4 because it is a nonpolar molecule with only London dispersion forces as its intermolecular force. London dispersion forces occur between all molecules, but they are the only intermolecular force present in nonpolar molecules like CH4. The other substances listed, such as CH3OH, NH, H2S, and HCl, have additional intermolecular forces such as hydrogen bonding or dipole-dipole interactions due to their polar nature.Rate this question:
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- 8.
Which of the following compounds will have hydrogen bonds as one of its intermolecular forces?
- A.
HF and NH3
- B.
SiH4 only
- C.
CH4 only
- D.
NH3 only
- E.
HF only
Correct Answer
A. HF and NH3Explanation
The presence of hydrogen bonding as an intermolecular force depends on the presence of hydrogen directly bonded to a highly electronegative atom such as fluorine (F), oxygen (O), or nitrogen (N).
Among the given compounds:
HF (hydrogen fluoride) has hydrogen bonding because hydrogen is directly bonded to fluorine.
NH3 (ammonia) has hydrogen bonding because hydrogen is directly bonded to nitrogen.Rate this question:
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- 9.
Which of the following should have the lowest boiling point?
- A.
PH3
- B.
H2S
- C.
HCl
- D.
SiH4
- E.
H2O
Correct Answer
D. SiH4Explanation
SiH4 (silane) should have the lowest boiling point among the given compounds. This is because SiH4 is a non-polar molecule with weak Van der Waals forces between its molecules. The other compounds (PH3, H2S, HCl, H2O) all have polar bonds and can form hydrogen bonds, which are stronger intermolecular forces. These stronger forces require more energy to break, resulting in higher boiling points for these compounds compared to SiH4.Rate this question:
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- 10.
Of the following substances, _____ has the highest boiling point.
- A.
H2O
- B.
CO2
- C.
CH4
- D.
Kr
- E.
NH3
Correct Answer
A. H2OExplanation
H2O has the highest boiling point among the given substances because it has strong hydrogen bonding between its molecules. Hydrogen bonding is a strong intermolecular force that requires a large amount of energy to break, resulting in a higher boiling point. CO2 and CH4 are nonpolar molecules and have weaker intermolecular forces, resulting in lower boiling points. Kr is a noble gas and exists as individual atoms, so it has very weak intermolecular forces and the lowest boiling point. NH3 has hydrogen bonding like H2O, but it is not as strong, so it has a lower boiling point than H2O.Rate this question:
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- 11.
The shape of a liquid 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
Correct Answer
C. The relative magnitudes of cohesive forces in the liquid and adhesive forces between the liquid and its containerExplanation
The shape of a liquid is determined by the relative magnitudes of cohesive forces in the liquid and adhesive forces between the liquid and its container. Cohesive forces are the attractive forces between molecules of the liquid, while adhesive forces are the attractive forces between the liquid and the container. If the cohesive forces are stronger than the adhesive forces, the liquid will form a convex meniscus and take the shape of a droplet. If the adhesive forces are stronger than the cohesive forces, the liquid will form a concave meniscus and spread out to take the shape of the container. Therefore, the relative magnitudes of these forces play a crucial role in determining the shape of a liquid.Rate this question:
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- 12.
What is the phase transition between solid to liquid?
- A.
Freezing
- B.
Melting
- C.
Depositing
- D.
Subliming
- E.
Vaporizing
Correct Answer
B. MeltingExplanation
The phase transition between solid to liquid is called melting. This process occurs when a solid substance absorbs enough heat energy to overcome the forces holding its particles together, causing them to move more freely and become a liquid.Rate this question:
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- 13.
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
Correct Answer
E. Supercritical fluid and gasExplanation
A supercritical fluid and gas is a substance that can expand to fill its container, similar to a gas, but also has a density approaching that of a liquid. It can also behave as a solvent, meaning it can dissolve other substances. This unique combination of properties makes it different from other states of matter like plasma, gas, liquid, and amorphous solid.Rate this question:
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- 14.
A substance whose triple point occurs at 222 K and 3.93 atm
- A.
Will melt rather than sublime at STP.
- B.
Will have a critical point of 211 K and 2.93 atm.
- C.
Will have a critical point of 233 K and 2.93 atm.
- D.
Will sublime rather than melt at STP.
- E.
Will not have a critical point.
Correct Answer
D. Will sublime rather than melt at STP.Explanation
The given information states that the substance has a triple point at 222 K and 3.93 atm. The triple point is the temperature and pressure at which all three phases of a substance (solid, liquid, and gas) can coexist in equilibrium. At STP (standard temperature and pressure), which is defined as 273 K and 1 atm, the substance will be at a higher temperature and pressure than its triple point. Since the substance has a higher temperature and pressure than its triple point at STP, it will sublime (change directly from a solid to a gas) rather than melt (change from a solid to a liquid) at STP.Rate this question:
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- 15.
A solid has a very high melting point, great hardness, and poor electrical conduction. This is a(n) ____________ solid.
- A.
Ionic
- B.
Molecular
- C.
Metallic
- D.
Covalent network
- E.
Both metallic and covalent network
Correct Answer
D. Covalent networkExplanation
A solid with a very high melting point, great hardness, and poor electrical conduction is likely a covalent network solid. Covalent network solids are held together by a network of covalent bonds, which are very strong and require a large amount of energy to break. This results in a high melting point. The strong bonds also contribute to the hardness of the solid. Covalent network solids do not have freely moving electrons, so they do not conduct electricity well. Therefore, based on the given properties, the solid is most likely a covalent network solid.Rate this question:
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- 16.
Metallic solids do not exhibit __________.
- A.
Excellent thermal conductivity.
- B.
Excellent electrical conductivity.
- C.
Variable hardness.
- D.
Extreme brittleness
- E.
Variable melting point.
Correct Answer
D. Extreme brittlenessExplanation
Metallic solids do not exhibit extreme brittleness. Metallic solids are known for their malleability and ductility, which means they can be easily bent or stretched without breaking. This is due to the presence of metallic bonds, which allow the atoms to move and slide past each other. Extreme brittleness, on the other hand, refers to the tendency of a material to break or shatter when subjected to stress. Metallic solids, with their ability to deform without fracturing, do not display this characteristic.Rate this question:
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- 17.
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
Correct Answer
C. CDExplanation
The heating curve shows the relationship between heat flow and temperature for a solid as it is heated. The slope of the CD segment corresponds to the heat capacity of the liquid phase of the substance. This means that during this segment, the substance is undergoing a phase change from a solid to a liquid, and the slope represents the amount of heat energy required to raise the temperature of the substance while it is in its liquid state.Rate this question:
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- 18.
The heat flow into the sample in the segment ________ will yield the value of the Hvap of this substance.
- A.
AB
- B.
BC
- C.
CD
- D.
DE
- E.
EF
Correct Answer
E. EFExplanation
The heat flow into the sample in the segment EF will yield the value of the Hvap (heat of vaporization) of this substance. This is because segment EF represents the phase transition from liquid to gas, and the heat flow during this transition is directly related to the heat of vaporization.Rate this question:
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- 19.
London dispersion forces result form the attraction between __________ and __________ dipoles.
Correct Answer
instantaneous, induced
induced, instantaneousExplanation
London dispersion forces result from the attraction between instantaneous and induced dipoles, as well as induced and instantaneous dipoles. These forces are a type of intermolecular force that occurs between all molecules, regardless of their polarity. Instantaneous dipoles are temporary fluctuations in electron distribution that create temporary dipoles, while induced dipoles are created in neighboring molecules due to the presence of an instantaneous dipole. The interaction between these temporary and induced dipoles leads to London dispersion forces.Rate this question:
- 20.
What two types of molecules exhibit London dispersion forces? _____________
Correct Answer
polar and nonpolar
nonpolar and polar - 21.
Viscosity is ___________________________.
Correct Answer
the resistance to flowExplanation
Viscosity refers to the resistance of a fluid to flow. It is a measure of the internal friction within a fluid, determining how easily it can flow or be deformed. The higher the viscosity, the thicker or more resistant the fluid is to flow. This property is essential in various applications, such as in the automotive industry for selecting the right motor oil or in the food industry for determining the consistency of sauces and liquids.Rate this question:
- 22.
X-Ray diffraction was used to make what important discovery?
Correct Answer
the helix structure of DNAExplanation
X-Ray diffraction is a technique that allows the determination of the 3D structure of molecules by analyzing the scattering pattern of X-rays. In the case of the helix structure of DNA, X-Ray diffraction was used to reveal the characteristic pattern of diffraction spots, indicating a regular repeating structure. This discovery was crucial in understanding the double helix structure of DNA, which provided insights into its replication, transcription, and genetic information storage.Rate this question:
- 23.
What are two real life examples of uses for supercritical fluid extraction?
Correct Answer
removing oils from potato chips, removing caffeine from coffeeExplanation
Supercritical fluid extraction is a technique used to separate and extract specific compounds from a substance using a supercritical fluid as the solvent. In the case of removing oils from potato chips, supercritical fluid extraction can be used to extract the oil content, resulting in a healthier and less greasy product. Similarly, in the case of removing caffeine from coffee, supercritical fluid extraction can selectively extract the caffeine while leaving behind other desirable compounds, allowing for the production of decaffeinated coffee. Both examples demonstrate the practical applications of supercritical fluid extraction in the food industry.Rate this question:
- 24.
Three structures of C are ________, ___________, and ___________.
Correct Answer
graphite, C60, diamond
C60, graphite, diamond
diamond, graphite, C60
C60, diamond, graphite
graphite, diamond, C60Explanation
The correct answer is graphite, C60, diamond. The three structures of C are graphite, C60, and diamond.Rate this question:
- 25.
In which group of elements would all members be expected to have very similar chemical properties?
- A.
O, S, Se
- B.
N, O, F
- C.
Na, Mg, K
- D.
S, Se, Si
- E.
Na, Ne, Mg
Correct Answer
A. O, S, SeExplanation
Oxygen (O), sulfur (S), and selenium (Se) are all elements in the same group on the periodic table, specifically Group 16 or the chalcogens. Elements in the same group tend to have similar chemical properties because they have the same number of valence electrons, which determines how they interact with other elements. In this case, O, S, and Se all have 6 valence electrons, so they are expected to have similar chemical properties such as forming similar types of compounds and exhibiting similar reactivity.Rate this question:
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- 26.
Electrons in the 1s subshell are much closer to the nucleus in Ar than in He due to the larger ________ in Ar.
- A.
Nuclear charge
- B.
Paramagnetism
- C.
Diamagnetism
- D.
Hund's rule
- E.
Azimuthal quantum number
Correct Answer
A. Nuclear chargeExplanation
The electrons in the 1s subshell are much closer to the nucleus in Ar than in He due to the larger nuclear charge in Ar. The nuclear charge refers to the positive charge of the nucleus, which attracts the negatively charged electrons. Since Ar has more protons in its nucleus compared to He, it has a greater nuclear charge. This stronger attraction pulls the electrons closer to the nucleus, resulting in a smaller average distance between the electrons and the nucleus in Ar compared to He.Rate this question:
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- 27.
Of the following, which gives the correct order for atomic radius for Mg, Na, P, Si and Ar?
- A.
Mg > Na > P > Si > Ar
- B.
Ar > Si > P > Na > Mg
- C.
Si > P > Ar > Na > Mg
- D.
Na > Mg > Si > P > Ar
- E.
Ar > P > Si > Mg > Na
Correct Answer
D. Na > Mg > Si > P > ArExplanation
The atomic radius is the distance from the nucleus to the outermost electron shell of an atom. It generally increases as you move down a group in the periodic table and decreases as you move across a period from left to right. In this case, the correct order for atomic radius is Na > Mg > Si > P > Ar. Sodium (Na) has the largest atomic radius because it is located in the first group of the periodic table, while Argon (Ar) has the smallest atomic radius because it is located in the noble gases group.Rate this question:
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- 28.
Screening by core electrons in atoms is ______________.
- A.
Less efficient than that by valence electrons.
- B.
More efficient than that by valence electrons.
- C.
Essentially identical to that by valence electrons.
- D.
Responsible for a general decrease in atomic radius going down a group
- E.
Both essentially identical to that by valence electrons and responsible for a general decrease in atomic radius going down a group
Correct Answer
B. More efficient than that by valence electrons.Explanation
Screening by core electrons in atoms refers to the shielding effect that occurs when the inner electrons of an atom partially block the attraction between the positively charged nucleus and the outer electrons. This shielding effect reduces the effective nuclear charge experienced by the outer electrons, making it easier for them to be removed or shared in chemical reactions. The question states that screening by core electrons is "more efficient" than that by valence electrons. This means that the core electrons provide a stronger shielding effect compared to the valence electrons, making it more effective in reducing the attraction between the nucleus and the outer electrons.Rate this question:
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- 29.
Which one of the following elements has the largest atomic radius?
- A.
Se
- B.
As
- C.
S
- D.
Sb
- E.
Te
Correct Answer
D. SbExplanation
Sb (antimony) has the largest atomic radius among the given elements. Atomic radius refers to the size of an atom, which is determined by the distance between the nucleus and the outermost electron shell. As you move down a group in the periodic table, the atomic radius generally increases due to the addition of more electron shells. Sb is located below Se, As, S, and Te in the periodic table, so it has more electron shells and therefore a larger atomic radius.Rate this question:
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