Understanding Pure Substances and Mixtures

What is the main objective of the lesson on pure substances and mixtures?

• To learn about the states of matter

• To understand chemical reactions

• To explore the periodic table

• To differentiate between pure substances and mixtures

Which of the following is an example of a pure substance?

• Silver

• Air

• Sand

• Salt water

What is a characteristic of elements?

• They are always synthetic

• They are mixtures of different atoms

• They are made up of one kind of atom

• They can be broken down by chemical means

Which of the following is a heterogeneous mixture?

• Salt water

• Water and sand

• Vinegar

• Blood plasma

How can a homogeneous mixture be described?

• It consists of only one element

• The components are easily identifiable

• The composition is uniform throughout

• It can be separated by hand picking

Which method is used to separate a liquid mixture by heating and cooling?

• Chromatography

• Filtration

• Decantation

• Simple distillation

What is the purpose of chromatography?

• To separate mixtures by size

• To separate mixtures by passing them through a medium

• To separate mixtures by heating

• To separate mixtures by cooling

Why is tap water considered a mixture?

• It contains impurities

• It is a compound

• It is distilled

• It is chemically pure

What process does distilled water undergo to become a pure substance?

• Distillation

• Evaporation

• Chromatography

• Filtration

What is the main difference between pure substances and mixtures?

• Pure substances have a definite composition

• Mixtures have uniform composition

• Pure substances are always liquids

• Mixtures are made of one type of atom