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AP Chemistry Practice Quiz: Properties of Solids

Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026

Test your understanding with short quizzes. This quiz has 15 questions to check your progress.

Question 1 of 15

A certain solid substance is brittle, has a high melting point, and conducts electricity only when it is dissolved in water. Based on this information, what type of solid is it?

All Questions (15)

A certain solid substance is brittle, has a high melting point, and conducts electricity only when it is dissolved in water. Based on this information, what type of solid is it?

A) Ionic solid

B) Molecular solid

C) Metallic solid

D) Covalent network solid

Correct Answer: A

The provided content states that ionic solids are brittle, have high melting points, and conduct electricity only when their ions are mobile, such as when they are molten or dissolved. These properties match the description perfectly.

Which of the following best explains why metallic solids are excellent conductors of heat and electricity?

A) The strong covalent bonds forming a rigid lattice.

B) The presence of mobile electrons within the solid structure.

C) The weak intermolecular forces between the metal atoms.

D) The fixed positions of ions in the crystal lattice.

Correct Answer: B

According to the provided content, metallic solids conduct heat and electricity due to the presence of mobile electrons. These electrons are not fixed to any single atom and can move freely throughout the solid.

Diamond and solid candle wax (a molecular solid) are both composed of nonmetal atoms. Why does diamond have a significantly higher melting point than candle wax?

A) Diamond is a metallic solid with strong metallic bonds.

B) Diamond has atoms held by strong covalent bonds in a 3D network, while wax has discrete molecules held by weak IMFs.

C) Diamond is an ionic solid with strong electrostatic attractions.

D) Diamond has mobile electrons that increase its thermal stability, while wax does not.

Correct Answer: B

The content explains that covalent network solids like diamond have atoms covalently bonded in a 3D network, resulting in high melting points. In contrast, molecular solids are composed of discrete molecules held together by weak IMFs, leading to low melting points. Melting diamond requires breaking strong covalent bonds, while melting wax only requires overcoming weak IMFs.

A substance has a very low vapor pressure at room temperature. What can be inferred about this substance?

A) It has weak intermolecular forces and a low boiling point.

B) It has strong intermolecular forces and a high boiling point.

C) It is a molecular solid with a low melting point.

D) It is a gas at room temperature.

Correct Answer: B

The content states that vapor pressure and boiling point are determined by the strength of intermolecular forces (IMFs). A low vapor pressure indicates that particles are not easily escaping into the gas phase, which is a characteristic of strong IMFs. Strong IMFs also lead to a high boiling point, as more energy is required to overcome them completely.

Graphite and diamond are both covalent network solids made of carbon atoms. However, graphite is soft and slippery, while diamond is extremely hard. What is the best explanation for this difference in macroscopic properties?

A) Graphite contains ionic bonds, while diamond contains only covalent bonds.

B) Graphite is structured in 2D layers with weak forces between them, while diamond has a rigid 3D network.

C) Graphite has a lower density than diamond.

D) Diamond has mobile electrons, making it harder than graphite.

Correct Answer: B

The provided text explicitly states that covalent network solids can be arranged in a 3D network or 2D layers. It specifies that 3D networks (like diamond) are hard, while 2D layers (like graphite) are soft. The softness of graphite comes from the ability of these layers to slide past one another.

A solid melts at a very low temperature (e.g., -50°C) and does not conduct electricity in either its solid or liquid state. This substance is best classified as a(n):

A) Ionic solid

B) Metallic solid

C) Molecular solid

D) Covalent network solid

Correct Answer: C

The content describes molecular solids as having low melting points and no electrical conductivity. These properties are due to the fact that they are composed of discrete molecules held together by weak intermolecular forces.

The specific function of many biomolecules, such as enzymes, is critically dependent on their three-dimensional shape. What is primarily responsible for maintaining this complex shape?

A) Strong covalent bonds forming a rigid network throughout the molecule.

B) The presence of mobile electrons shared across the entire biomolecule.

C) Noncovalent interactions (IMFs) between different parts of the molecule.

D) Strong metallic bonds between atoms in the biomolecule.

Correct Answer: C

The provided text states that in biomolecules and polymers, noncovalent interactions (a term for IMFs in this context) dictate the molecular shape, which is crucial for their function and properties.

When copper and zinc are melted together to form the alloy brass, which property of a metallic solid is typically retained?

A) Brittleness

B) Low melting point

C) Electrical conductivity

D) Solubility in water

Correct Answer: C

The content specifies that alloys, which are mixtures of metals, typically remain conductive. This is because the mobile electrons responsible for conductivity in pure metals are still present in the alloy's structure.

Which statement best describes the relationship between the particulate-level structure of an ionic solid and its macroscopic properties?

A) Mobile electrons surrounding a cation lattice lead to malleability and conductivity.

B) Discrete molecules held by weak IMFs lead to low melting points and softness.

C) A rigid lattice of alternating positive and negative ions held by strong electrostatic forces leads to a high melting point and brittleness.

D) A network of atoms connected by covalent bonds in 2D layers leads to softness and high melting points.

Correct Answer: C

This question connects the particulate-level structure to macroscopic properties as described in the content. Ionic solids have high melting points and are brittle. This is due to their structure: a strong, rigid lattice of ions. The other options describe metallic, molecular, and covalent network (graphite) solids, respectively.

Of the following solid types, which is generally expected to have the lowest melting point?

A) Ionic solid

B) Covalent network solid

C) Metallic solid

D) Molecular solid

Correct Answer: D

The content states that molecular solids are held together by weak IMFs, which leads to low melting points. Ionic, covalent network, and metallic solids all involve much stronger forces (electrostatic attraction, covalent bonds, metallic bonds), which require more energy to overcome, resulting in higher melting points.

The process of vaporization (boiling) requires completely overcoming intermolecular forces. Which substance would require the most energy to vaporize a mole of the substance from its liquid state?

A) A substance with very weak IMFs.

B) A substance with a high vapor pressure.

C) A substance with a low boiling point.

D) A substance with very strong IMFs.

Correct Answer: D

The content states that vaporization overcomes IMFs completely and that boiling point is directly related to IMF strength. Therefore, a substance with very strong IMFs will require the most energy to overcome those forces and will have the highest boiling point.

Silicon dioxide (SiO2), the main component of sand, has an extremely high melting point (over 1700°C) and is very hard. How is SiO2 classified?

A) As an ionic solid, due to the difference in electronegativity between Si and O.

B) As a covalent network solid, where atoms are bonded in a continuous network.

C) As a molecular solid, consisting of individual SiO2 molecules.

D) As a metallic solid, because silicon is a metalloid.

Correct Answer: B

The content explicitly lists SiO2 as an example of a covalent network solid. Its properties of having a high melting point and being hard are characteristic of 3D covalent network solids.

Why are metallic solids malleable and ductile, while ionic solids are brittle?

A) Metallic bonds are weaker than ionic bonds.

B) In metals, the mobile electron sea can adjust to shifting cations, whereas in ionic solids, shifting ions causes like-charge repulsion that shatters the crystal.

C) Metals are made of discrete atoms, while ionic solids are made of molecules.

D) Ionic solids have higher melting points, which makes them less flexible than metals.

Correct Answer: B

The content explains that metals are malleable/ductile due to mobile electrons. While not explicitly stated, the brittleness of ionic solids is the contrasting property. The mobile electrons in a metal allow the cations to slide past one another without breaking the metallic bond. In an ionic solid, a similar shift would align ions with like charges, causing strong repulsion and fracturing the solid. This connects the particulate-level structure to the macroscopic property.

The macroscopic properties of a substance, such as its melting point and hardness, are ultimately determined by:

A) The number of protons in the nucleus of its atoms.

B) The temperature and pressure of the surroundings only.

C) Its particulate-level structure and the interactions between its particles.

D) The mass of a single molecule or formula unit.

Correct Answer: C

This is a direct application of the first point in the provided content, which states that there is a relationship among the macroscopic properties, the particulate-level structure, and the interactions between particles (IMFs or bonds).

Particulate-level representations are useful for explaining macroscopic properties. Which representation would best explain why a molecular solid has a low boiling point?

A) A diagram showing a rigid 3D network of covalently bonded atoms.

B) A diagram showing positive ions in a sea of mobile electrons.

C) A diagram showing an ordered lattice of positive and negative ions.

D) A diagram showing discrete molecules with weak forces of attraction between them.

Correct Answer: D

The content states that molecular solids have low melting points due to weak IMFs between discrete molecules. A particulate-level diagram showing separate molecules with weak attractions (often depicted as dashed lines) would best represent this structure and explain why little energy is needed to overcome these forces for boiling or melting.