Elements, Compounds and Mixtures Intro

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.

When electricity passes through water, hydrogen and oxygen are produced. Which table correctly labels the compounds and elements involved in the process?

• Water-->Compound

  Hydrogen-->Compound

  Oxygen--->Element

• Water-->Compound

  Hydrogen--->Element

  Oxygen--->Compound

• Water--->Compound

  Hydrogen--->Element

  Oxygen--->Element

Tags

NGSS.MS-PS1-1

When electricity passes through water, hydrogen and oxygen are produced. Which table correctly labels the compounds and elements involved in the process?

• Water-->Compound

  Hydrogen-->Compound

  Oxygen--->Element

• Water-->Compound

  Hydrogen--->Element

  Oxygen--->Compound

• Water--->Compound

  Hydrogen--->Element

  Oxygen--->Element

Tags

NGSS.MS-PS1-1

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

Tags

NGSS.MS-PS1-1

Which changes MUST happen for elements to become a compound?

• elements are heated

• a gas becomes a liquid

• elements dissolve in water

• chemical bonds form between atoms.

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

• atom

• liquid

• mixture

• compound

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

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.

This image is a model of...

• an element

• a compound

• a homogenous mixture

• a heterogeneous mixture

Tags

NGSS.MS-PS1-1