What is a pure substance - bread, salt, seawater, or soil?

Salt is the pure substance out of them all.

Salt is a pure substance. Pure substances are composed of one type of molecule. All of the substances listed are composed of two or more types of molecules, except for salt. Therefore, salt would be your answer.

Hope this helps.

shield volcanos are angry and get mad over the smallest things so much that there heads erupt   pahoehoe and a'a lava. a composite volcano is the poller opposite of a shield volcano. its   peaceful thing and knows how to control its emotions.