AP Physics 2: Algebra-Based Practice Quiz: The Ideal Gas Law

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

Test your understanding with short quizzes. This quiz has 11 questions to check your progress.

Question 1 of 11

According to the classical model, which of the following is a key assumption about the atoms of an ideal gas?

A)The atoms are in fixed positions within the container.B)The atoms experience significant long-range attractive forces.C)The volumes of the atoms are negligible compared to the total volume.D)The collisions between atoms are inelastic, conserving momentum but not kinetic energy.

All Questions (11)

According to the classical model, which of the following is a key assumption about the atoms of an ideal gas?

A) The atoms are in fixed positions within the container.

B) The atoms experience significant long-range attractive forces.

C) The volumes of the atoms are negligible compared to the total volume.

D) The collisions between atoms are inelastic, conserving momentum but not kinetic energy.

Correct Answer: C

The provided content states that the classical model of an ideal gas assumes 'the volumes of the atoms are negligible compared to the total volume occupied by the gas'. The other options contradict the assumptions of random motion, elastic collisions, and forces only occurring during collisions.

In the ideal gas law equation, $PV=nRT$, what does the variable 'n' represent?

A) The number of atoms in the gas

B) The number of moles of the gas

C) Avogadro's number

D) The density of the gas in moles per liter

Correct Answer: B

The content explicitly mentions that the ideal gas equation, $PV=nRT$, models the relationship between pressure, volume, 'the number of moles or number of atoms', and temperature. In the form using the gas constant R, 'n' specifically represents the number of moles.

A key assumption of the ideal gas model is that collisions between atoms are elastic. What does this imply?

A) The atoms stick together after colliding.

B) Both momentum and kinetic energy are conserved during collisions.

C) Only momentum is conserved, while kinetic energy is lost as heat.

D) The total volume of the gas decreases after each collision.

Correct Answer: B

The provided content states that 'the atoms collide elastically'. An elastic collision, by definition, is one in which the total kinetic energy of the colliding objects is conserved, in addition to the total momentum. The other options describe inelastic collisions or are unrelated to the concept.

A scientist plots the pressure of a fixed amount of an ideal gas in a rigid container as a function of its temperature. By extrapolating the resulting line to the point where the pressure is zero, what can be determined?

A) The boiling point of the gas

B) The critical pressure of the gas

C) The temperature at which the gas becomes a solid

D) A temperature of absolute zero

Correct Answer: D

The content states, 'A temperature at which an ideal gas has zero pressure can be extrapolated from a graph of pressure as a function of temperature.' This theoretical temperature, where an ideal gas would exert no pressure, is absolute zero (0 Kelvin).

The ideal gas law can be expressed as $PV=Nk_{B}T$. In this form of the equation, what does the variable 'N' represent?

A) The number of moles of the gas

B) The number of atoms of the gas

C) The normality of the gas solution

D) The neutron number of the gas atoms

Correct Answer: B

The provided text gives two forms of the ideal gas law, stating the relationships involve 'the number of moles or number of atoms'. The equation $PV=nRT$ uses 'n' for moles, while the alternative form $PV=Nk_{B}T$ uses 'N' to represent the total number of atoms (or molecules) and $k_{B}$ for the Boltzmann constant.

According to the ideal gas law ($PV=nRT$), if the volume and temperature of a gas are held constant, how does the pressure change if the number of moles (n) of the gas is doubled?

A) The pressure is halved.

B) The pressure is quadrupled.

C) The pressure is doubled.

D) The pressure remains unchanged.

Correct Answer: C

From the equation $PV=nRT$, if V, R, and T are constant, pressure (P) is directly proportional to the number of moles (n). Therefore, if the number of moles is doubled, the pressure must also double to maintain the equality.

Which of the following is NOT an assumption of the classical model of an ideal gas?

A) The instantaneous velocities of atoms are random.

B) Atoms exert continuous, long-range attractive forces on each other.

C) The only appreciable forces on the atoms are those that occur during collisions.

D) The atoms collide elastically with each other and the container walls.

Correct Answer: B

The provided text explicitly states that 'the only appreciable forces on the atoms are those that occur during collisions'. This means the model assumes there are no significant long-range forces (like attraction or repulsion) between the atoms, making option B the incorrect statement and thus the correct answer.

A graph is created to model the properties of an ideal gas, with pressure on the y-axis and volume on the x-axis, while the temperature and number of moles are kept constant. What would be the general shape of the curve?

A) A straight line with a positive slope passing through the origin.

B) A straight line with a negative slope.

C) A hyperbola.

D) A parabola opening upwards.

Correct Answer: C

The ideal gas law is $PV=nRT$. If n and T are constant, then PV = constant. This describes an inverse relationship between pressure and volume ($P = constant/V$). A graph of an inverse relationship, such as y=k/x, is a hyperbola. The content mentions that graphs can be used to describe properties of the gas.

When are the forces on the atoms of an ideal gas considered to be appreciable, according to the classical model?

A) Only during collisions

B) At all times due to intermolecular attraction

C) Never, as ideal gas atoms are assumed to have no forces

D) When the temperature of the gas is very high

Correct Answer: A

The source text specifies that one of the assumptions of the classical ideal gas model is that 'the only appreciable forces on the atoms are those that occur during collisions'. This means forces are negligible at all other times.

The assumption that the volume of gas atoms is negligible compared to the total volume is a key part of the ideal gas model. This assumption is most likely to be valid under which conditions?

A) High pressure and low temperature

B) Low pressure and high temperature

C) High pressure and high temperature

D) Low pressure and low temperature

Correct Answer: B

The model assumes atom volumes are negligible compared to the total volume. Low pressure and high temperature cause the gas to expand and occupy a large total volume, making the volume of the individual atoms comparatively smaller and the assumption more valid. The provided content implies this by stating the assumptions used to model the gas with the ideal gas law.

Based on the ideal gas law ($PV=nRT$), what is the relationship between the volume (V) and absolute temperature (T) of a gas if the pressure (P) and number of moles (n) are held constant?

A) Volume is inversely proportional to temperature.

B) Volume is directly proportional to temperature.

C) Volume is proportional to the square of the temperature.

D) There is no relationship between volume and temperature.

Correct Answer: B

The ideal gas law equation is $PV=nRT$. If P, n, and R are all constant, the equation can be rearranged to V = (nR/P)T. Since the term (nR/P) is a constant, this shows that volume (V) is directly proportional to the absolute temperature (T). This relationship can be determined from the provided equation.