C2 Atoms, Elements, Molecules, Mixtures, and Compounds

What is a molecule?

• A group of two or more atoms held together by chemical bonds

• A substance that contains two or more different elements

• A mixture of two or more substances that are not chemically combined

• A single atom

Which of the following are examples of a molecule?

• Carbon dioxide

• Oxygen

• Water

• Helium

What is a compound?

• A single atom

• A mixture of two or more substances that are not chemically combined

• A substance that contains two or more different elements

• A group of two or more atoms held together by chemical bonds

Which of the following is an example of a compound?

• Chlorine

• Helium

• Water

• Oxygen

What is the formula for water?

• NaCl

• H₂O

• H₂SO₄

• CO₂

What is the formula for carbon dioxide?

• H₂O

• CO₂

• CO

• H₂SO₄

What is the formula for calcium hydroxide?

• CaO

• CaOH

• CaOH₂

• Ca(OH)₂

Which of the following is true about mixtures?

• They are a single atom

• They are a group of two or more atoms held together by chemical bonds

• They are substances that contain two or more different elements

• They are two or more substances that are not chemically combined

How can mixtures be separated?

• Through chemical reactions

• Through gravitational separation

• Through physical methods like filtration, crystallization, or distillation

• Through nuclear reactions

What is a substance that cannot be broken down into simpler substances by chemical means?

• A compound

• An element

• A mixture

• A molecule