DENSITY, MATTER, PHYSICAL & CHEMICAL CHANGES

Which of the following is NOT a pure substance?

• NaCl
• CO
• Sweet tea
• CO₂

Which of the following is NOT an element?

• Na
• Cl
• H20
• N

What makes compounds different from mixtures is:

• Mixtures are made up of two or more elements that are chemically combined while compounds are not chemically combined. 
• Compounds are made up of two or more different elements that are chemically combined while mixtures are not chemically combined. 
• Compounds are pure substances that consist of identical atoms that cannot be broken down into simpler substances. 
• Mixtures are pure substances that consist of identical atoms that cannot be broken down into simpler substances.  

An example of a heterogeneous mixture is:

• Chocolate milk
• Sand
• Tea
• Black coffee

Homogeneous mixtures:

• Are uniform throughout. 
• Are non-uniform throughout. 
• Are pure substances that require a chemical reaction to be broken down. 
• Are made up of two or more different elements that are chemically combined. 

All matter can be placed into two categories.  These categories are:

• Homogeneous and heterogeneous mixtures. 
• Compounds and elements. 
• Mixtures and compounds. 
• Pure substances and mixtures.