Changes in Matter and Law of Conservation of Mass

Matter can undergo physical and chemical changes. A physical change is a change of matter from one form to another without a change in the identity of the substance. Which process is an example of a physical change?

• ice melting
• milk souring
• metal rusting
• wood burning

Which process is an example of a physical change?

• burning
• rusting
• flattening
• Decomposing

Some properties, such as mass, depend on how much matter is present. Other properties, such as malleability, remain the same no matter how much matter is present. Which of these choices is a physical property of the element potassium that remains the same no matter how much matter is present?

• reactivity
• flammability
• melting point
• volume

Which process is an example of a physical change?

• Carrots are cut into small pieces and mixed into a salad
• A peanut butter sandwich is eaten and broken down by enzymes in the stomach
• Sodium metal and water are combined to form a basic compound and a flammable gas
• Sodium metal and chlorine gas are combined to form sodium chloride, or table salt.

It is important to understand the differences between chemical and physical changes. Chemical changes result in new substances, but physical changes do not. Which process is an example of a physical change?

• Water turns to steam when boiled over a Bunsen burner.
• Carbon combines with oxygen to form carbon dioxide gas.
• Water breaks down into hydrogen and oxygen gases over time.
• Limestone breaks down into lime and carbon dioxide when heated.

—a paper clip, a pair of scissors, a needle, and a horseshoe. Assume that each object is made of the same metal. Which of these physical properties is not similar in all four of these objects?

• mass
• magnetism
• specific heat
• electrical conductivity

Matter can go through two types of changes: physical changes and chemical changes. Chemical changes result in new substances, while physical changes do not. Which process is an example of a physical change?

• paper burning into ash
• dough being baked into bread
• apple juice turning into vinegar
• rock being crushed into gravel

Pablo notices that ice cream begins to melt when left out at room temperature. What is Pablo observing?

• a physical change
• a chemical change
• a chemical reaction
• the formation of a new substance

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Marco tears a piece of notebook paper into smaller pieces, as shown below. Tearing paper into pieces is an example of what kind of change?

• a change in mass
• a physical change
• a chemical change
• a change in energy

The two beakers shown below contain pure water. Which of these properties is the same for the water in both beakers?

• mass
• weight
• volume
• density