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AP Chemistry Practice Quiz: Introduction for Reactions

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

Test your understanding with short quizzes. This quiz has 9 questions to check your progress.

Question 1 of 9

According to the provided information, which statement best defines a physical change?

All Questions (9)

According to the provided information, which statement best defines a physical change?

A) A change where a substance is transformed into a new substance.

B) A change that alters the properties of a substance but not its chemical composition.

C) A change that is always accompanied by the production of heat or light.

D) A change that results in the formation of a gas or a precipitate.

Correct Answer: B

The provided content explicitly states that a physical change alters properties but not composition. The other options describe evidence of or the definition of a chemical change.

Which of the following processes is described as a physical change?

A) A log burning in a fireplace, producing light and heat.

B) An iron nail rusting, indicated by a color change.

C) An antacid tablet fizzing and forming a gas in water.

D) Ice melting into liquid water, which is a phase change.

Correct Answer: D

The content identifies phase changes, such as melting, as a type of physical change because the chemical composition of the substance (H2O) remains the same. The other options describe evidence of chemical changes (production of heat/light, color change, gas formation).

A student mixes two clear liquids in a beaker. They observe the formation of a solid material that was not present before. This observation is evidence of what kind of change?

A) A chemical change, indicated by the formation of a precipitate.

B) A physical change, indicated by the formation of a mixture.

C) A chemical change, indicated by a phase change.

D) A physical change, indicated by a color change.

Correct Answer: A

The formation of a solid from a solution (precipitate) is listed as possible evidence that a chemical change has occurred, transforming the original substances into a new one.

The fundamental difference between a chemical change and a physical change is that a chemical change involves a transformation of the substance's...

A) state of matter.

B) temperature.

C) chemical composition.

D) physical properties.

Correct Answer: C

The provided text distinguishes the two by stating a physical change does not alter composition, while a chemical change transforms substances into new substances, which implies a change in chemical composition.

Which of the following observations would be the LEAST conclusive evidence on its own for a chemical change?

A) A bright light is produced when two substances are mixed.

B) A solid forms when two aqueous solutions are combined.

C) The temperature of a solution changes when a substance is dissolved in it.

D) Bubbles are seen escaping from a liquid after a solid is added.

Correct Answer: C

While the production of heat is evidence of a chemical change, some physical changes (like dissolving certain salts in water) can also cause a temperature change. The other options (light production, precipitate formation, gas formation) are stronger indicators of a new substance being formed.

A student is tasked with separating a mixture of sand and salt. They add water to the mixture, stir until the salt dissolves, and then pour the water through a filter to collect the sand. Finally, they boil the water away to recover the solid salt. How many chemical changes occurred during this procedure?

A) 0

B) 1

C) 2

D) 3

Correct Answer: A

The entire process involves only physical changes. Dissolving the salt is forming a mixture, filtering is separating a mixture, and boiling the water is a phase change. None of these steps alter the chemical composition of the salt, sand, or water.

All of the following are explicitly listed as possible evidence of a chemical change EXCEPT:

A) Formation of a gas.

B) Production of heat.

C) Change in mass.

D) Change in color.

Correct Answer: C

The provided content lists production of heat/light, gas formation, precipitate formation, and/or color change as possible evidence. A change in mass is not mentioned as an indicator and relates to the law of conservation of mass.

Which pair of processes correctly identifies one physical change and one chemical change?

A) Physical: water boiling; Chemical: ice melting

B) Physical: separating a mixture; Chemical: a substance changing color

C) Physical: a gas forming; Chemical: a precipitate forming

D) Physical: production of light; Chemical: separating a mixture

Correct Answer: B

According to the text, separating a mixture is a physical change, and a color change is possible evidence of a chemical change. Option A lists two physical changes. Options C and D list evidence of chemical changes as physical changes.

A substance undergoes a change, resulting in the production of a gas and a noticeable glow of light. This event is best classified as a chemical change because:

A) the substance changed its phase from solid/liquid to gas.

B) the observations match the listed evidence for the formation of new substances.

C) any change involving energy is, by definition, a chemical change.

D) the properties of the substance were altered, which defines a chemical change.

Correct Answer: B

The production of gas and light are two of the key pieces of evidence provided in the text that suggest a chemical change—a transformation into a new substance—has occurred. While a phase change (A) is a change to a gas, the accompanying production of light strongly indicates a chemical reaction. Option D is an incomplete definition, as physical changes also alter properties.