8th Grade Science – Unit 1 STAAR Practice Exam

Which of the following is an example of a physical property?

• Flammability

• Density

• Reactivity with acid

• Ability to rust

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NGSS.MS-PS3-1

The chemical formula for carbon dioxide is CO₂. How many oxygen atoms are in three molecules of carbon dioxide?

• 2

• 3

• 6

• 9

Tags

NGSS.MS-PS1-1

Which best describes the Law of Conservation of Mass?

• Matter can be created but not destroyed.

• Matter can be destroyed but not created.

• Matter is neither created nor destroyed in chemical reactions.

• Matter is lost when substances burn.

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NGSS.MS-PS1-5

Which observation best indicates a chemical change?

• Ice melting

• Color change

• Water boiling

• Breaking a glass

Tags

NGSS.MS-PS1-5

NGSS.MS-PS1-2

A beaker of vinegar is mixed with baking soda and bubbles appear. This is evidence of:

• A physical change

• A chemical change

Tags

NGSS.MS-PS1-5

NGSS.MS-PS1-2

Which of the following is a compound?

• Na

• O₂

• H₂O

• Fe

Tags

NGSS.MS-PS1-1

Why is density a useful property for identifying a substance?

• It changes depending on sample size.

• It is unique for each pure substance.

• It is the same for all substances.

• It can only be measured in solids.

Which statement correctly distinguishes between mixtures and compounds?

• Mixtures are chemically bonded, compounds are not.

• Compounds can be separated by physical means, mixtures cannot.

• Mixtures vary in composition, compounds have fixed ratios.

• Compounds are always solids, mixtures are always liquids.

When iron reacts with oxygen to form rust, what is produced?

• A new compound with different properties

• A mixture with the same properties

• An element with fewer atoms

• A physical change with no new substance

Tags

NGSS.MS-PS1-5

NGSS.MS-PS1-2

The chemical formula C₆H₁₂O₆ contains how many total atoms?

• 3

• 6

• 12

• 24

Tags

NGSS.MS-PS1-1