Properties of Matter — Answer Key
Part A: Fix the Sentence
Each sentence has an error. Rewrite it correctly on the line.
1. Fix the sentence:
Flammability is a physical property because you can see a material catch fire.
Corrected: Flammability is a chemical property because the material changes into a new substance when it burns.
The corrected sentence is: "Flammability is a chemical property because the material changes into a new substance when it burns.". The original sentence "Flammability is a physical property because you can see a material catch fire." contained an error that needed to be fixed.
2. Fix the sentence:
The color of a rock is a chemical property because you must test it in a lab.
Corrected: The color of a rock is a physical property because you can observe it without changing the substance.
The corrected sentence is: "The color of a rock is a physical property because you can observe it without changing the substance.". The original sentence "The color of a rock is a chemical property because you must test it in a lab." contained an error that needed to be fixed.
3. Fix the sentence:
Density is a chemical property because you need to measure both mass and volume.
Corrected: Density is a physical property because measuring mass and volume does not change the substance.
The corrected sentence is: "Density is a physical property because measuring mass and volume does not change the substance.". The original sentence "Density is a chemical property because you need to measure both mass and volume." contained an error that needed to be fixed.
Part B: Fill in the Blank
Write the missing word or number on each line.
1. A physical property can be observed without changing the composition of a substance.
Physical properties (color, mass, volume, state) can be measured without changing what the substance is made of.
2. The ability of a substance to rust when exposed to oxygen is a chemical property.
Reactivity with oxygen (rusting) is a chemical property — it describes how a substance changes into a new substance.
3. Mass, volume, and color are all examples of physical properties.
Physical properties can be observed or measured without changing the substance's chemical identity.
4. A chemical property describes how a substance reacts with other substances.
Chemical properties describe how a substance interacts with other substances to form new materials.
Part C: Short Answer
Answer each question in one or two complete sentences.
1. Name two physical properties and two chemical properties of a piece of iron.
Sample answer: Two physical properties of iron are its silver color and its hardness. Two chemical properties are its ability to rust when exposed to moisture and its flammability at very high temperatures.
Physical: observable traits. Chemical: how it reacts (rusting=reacts with oxygen; flammability=reacts with oxygen by burning).
2. Why is boiling point considered a physical property and not a chemical property?
Sample answer: Boiling point is a physical property because when a liquid boils it changes state from liquid to gas but remains the same substance. No new substance is created, so it is not a chemical change.
State changes are physical changes. Water boiling is still water — just in gas form (steam).