What is the smallest unit of matter that makes up all physical substances?

• Element

• Compound

• Atom

• Molecule

Which of the following is a physical change of water?

• Water decomposing into steam

• Water reacting with sodium

• Water freezing into ice

• Water turning into hydrogen and oxygen

What is a compound?

• A physical state of matter

• A mixture of elements and compounds

• A new substance formed by combining different atoms

• A single element

How is a pure substance different from a mixture?

• A mixture is chemically bonded

• A pure substance has consistent properties throughout

• A pure substance has varying properties throughout

• A mixture cannot be separated into its components

What happens to the physical properties of water when salt is added?

• They become identical to pure salt

• They remain the same as pure water

• They become a new compound

• They change and differ from both pure water and pure salt