List and describe two differences between pure substances and mixtures. Check all that apply. Check all that apply. The composition of a pure substance depends on the source, but the composition of a mixture doesn't depend on the source. The composition of a pure substance is always the same, regardless of the source, but the composition of a mixture can vary. The state of a pure substance is always the same, but the state of a mixture can vary. Mixtures can be separated into their components only by chemical changes; some pure substances can be separated into components by physical change. Mixtures can be separated into their components by physical changes; some pure substances can be separated into components by chemical change.

The composition of a pure substance is always the same, regardless of the source, but the composition of a mixture can vary.

Mixtures can be separated into their components by physical changes; some pure substances can be separated into components by chemical change.

Explanation:

A chemically pure substance has a well defined and constant composition. The composition of a chemically pure substance remains the same irrespective of its source. Also, the components of a chemically pure substance may be separated by chemical changes.

Mixtures have a variable composition depending on their  respective sources. The composition of a mixture varies with the source of the mixture and mixtures are separated by physical processes.

- lead + phosphoric acid = hydrogen + lead(ii) phosphate