7th Grade Science Unit 1 Review

Which of the following is a compound?

• Oxygen (O₂)

• Sodium (Na)

• Carbon dioxide (CO₂)

• Gold (Au)

Tags

NGSS.MS-PS1-1

How many atoms are in one molecule of methane, CH₄?

• 2

• 4

• 5

• 6

Tags

NGSS.MS-PS1-1

Which statement correctly describes compounds?

• They can be separated by physical means.

• They contain two or more different elements chemically combined.

• They are made of only one type of atom.

• They are always gases at room temperature.

Select all that are elements.

• Nitrogen (N₂)

• Glucose (C₆H₁₂O₆)

• Hydrogen (H₂)

• Sodium chloride (NaCl)

In the chemical formula Al₂O₃, how many atoms of aluminum are present?

• 1

• 2

• 3

• 5

Tags

NGSS.MS-PS1-1

The compound calcium hydroxide, Ca(OH)₂, contains:

• 1 atom of calcium, 2 atoms of oxygen, 2 atoms of hydrogen

• 1 atom of calcium, 2 atoms of oxygen, 1 atom of hydrogen

• 2 atoms of calcium, 1 atom of oxygen, 2 atoms of hydrogen

• 1 atom of calcium, 1 atom of oxygen, 2 atoms of hydrogen

Tags

NGSS.MS-PS1-1

Which formula represents a compound made of three different elements?

• O₂

• H₂O

• NaCl

• C₆H₁₂O₆

Tags

NGSS.MS-PS1-1

Which of the following is the best evidence of a chemical change?

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Which process shows a physical change?

• Baking a cake

• Rust forming on iron

• Salt dissolving in water

• Wood burning in a campfire

Which statement about mixtures is correct?

• They are always evenly mixed.

• They can be separated by physical means.

• They are chemically bonded substances.

• They are always liquid.