Understanding Elements, Compounds, and Mixtures

What is the smallest unit of an element that retains the properties of that element?

• Molecule

• Atom

• Compound

• Mixture

Which of the following is a compound?

• Oxygen

• Water

• Iron

• Helium

Which of the following is a mixture?

• Salt

• Carbon dioxide

• Air

• Hydrogen

What is the chemical formula for water?

Which of the following is an element?

• Sugar

• Gold

• Salt

• Water

Which of the following statements is true about compounds?

• They can be separated by physical means.

• They are made up of two or more elements chemically combined.

• They are always gases.

• They are the same as mixtures.

Which of the following is a homogeneous mixture?

• Salad

• Sand and water

• Saltwater

• Oil and water

What is the main difference between a compound and a mixture?

• Compounds are always solid, mixtures are always liquid.

• Compounds have a fixed composition, mixtures do not.

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

• Compounds are made of one element, mixtures are made of two.

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

• Vinegar

• Milk

• Soil

• Pure water

What is the chemical symbol for the element Iron?

• Fe

• Ir

• In

• I