Elements vs. Compounds. Vs. Mixtures

Which of the following is an example of the formation of a mixture?

• Rust forming on an iron nail.

• Sugar crystals dissolving in water.

• Sodium and chlorine forming table salt.

• Hydrogen and oxygen reacting to produce oxygen.

Which statement identifies why oxygen is classified as a pure substance and air is classified as a mixture?

• Oxygen is more reactive than air.

• Oxygen has a higher density than air.

• Oxygen goes under a phase change, whereas air is always a gas.

• Oxygen contains only one substance, but air contains several substances.

Which of the following is an example of of a container filled with a pure substance rather than with a mixture?

• A tire filled with air.

• A jar filled with salt water.

• A balloon filled with helium.

• A glass filled with chocolate milk.

The chemical equation shown below represents a reaction that produces fuel for certain cars.

CO + H₂O------->CO₂ + H₂

_{Which substance in this equation is classified as an element?}

• CO

• O₂

• CO₂

• H₂

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NGSS.MS-PS1-1

Water (H₂O), is not found on the periodic table because water is a...

• atom

• liquid

• mixture

• compound

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NGSS.MS-PS1-1

Which of the following explains why saltwater is considered a mixture?

• It is composed of one element.

• It is composed of one compound.

• It is composed of two or more substances and has new chemical properties.

• It is composed of two or more substances and retains their own chemical properties.

Oxygen and iron combine chemically to form rust. Rust is classified as which of the following?

• an atom.

• an element.

• a compound.

• a mixture.

Tags

NGSS.MS-PS1-1

This image is a model of...

• an element

• a compound

• a homogenous mixture

• a heterogeneous mixture

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NGSS.MS-PS1-1

This picture is a model of...

• an element

• a compound

• a homogenious mixture

• a heterogeneous mixture.

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NGSS.MS-PS1-1

The image below is an example of

• a homogeneous mixture

• a compound

• a heterogeneous mixture

• an element