Properties of Matter — Answer Key
Part A: Fill in the Blank
Write the missing word or number on each line.
1. Density equals mass divided by volume, and it tells how tightly packed matter is.
The density formula is mass divided by volume. Volume is the denominator because density measures how much mass fits into each unit of space.
2. The density of pure water is about 1 gram per cubic centimeter.
Pure water's density is 1 g/cm³, which means one cubic centimeter of water has a mass of one gram. Scientists use this value as a benchmark for comparing the densities of other materials.
3. An object that floats in water must have a density less than 1 g/cm³.
Objects float when they are less dense than the liquid they are placed in. Since water's density is 1 g/cm³, anything below that value will float.
4. A graduated cylinder is used to measure the volume of a liquid in milliliters.
A graduated cylinder has measurement lines marked along its side, allowing you to read the volume of a liquid accurately in milliliters.
5. If a block has a mass of 20 g and a volume of 10 cm³, its density is 2 g/cm³.
Using the formula density = mass / volume, 20 g divided by 10 cm³ equals 2 g/cm³. This block would sink in water because its density is greater than 1 g/cm³.
6. Two objects can have the same volume but different masses because they are made of different materials.
Different materials pack different amounts of matter into the same space. A wooden block and an iron block the same size have different masses because iron is a denser material than wood.
7. When you place an object in water and it sinks, its density is greater than water.
An object sinks when it is denser than the liquid around it. Since water has a density of 1 g/cm³, a sinking object must have a density greater than that.
8. The water displacement method measures volume by seeing how much the water level rises.
When you drop an object into water, the object pushes the water aside and the water level rises. The amount of rise equals the volume of the submerged object.
9. Density is a physical property because it stays the same no matter how much of the substance you have.
Density is a physical property because you can measure it without changing the substance into something new. A small sample of iron and a large sample of iron both have the same density.
Part B: Matching
Match each item on the left to the correct answer on the right.
1. Match each item to its correct answer.
Cork
→ Floats — density around 0.24 g/cm³, much lighter than water
Sinks — very high density metal, about 19.3 g/cm³
Steel nail
→ Sinks — density about 7.8 g/cm³, much denser than water
Floats — density around 0.92 g/cm³, lighter than water
Vegetable oil
→ Floats — density around 0.92 g/cm³, lighter than water
Sinks — density about 7.8 g/cm³, much denser than water
Gold coin
→ Sinks — very high density metal, about 19.3 g/cm³
Floats — density around 0.24 g/cm³, much lighter than water
Correct matches: Cork → Floats — density around 0.24 g/cm³, much lighter than water; Steel nail → Sinks — density about 7.8 g/cm³, much denser than water; Vegetable oil → Floats — density around 0.92 g/cm³, lighter than water; Gold coin → Sinks — very high density metal, about 19.3 g/cm³.