Answer:
A substance containing only one type of atom or one type of molecule is a pure substance. Most of the matter around us, however, consists of mixtures of pure substances. Air, wood, rocks and dirt are examples of such mixtures. Mixtures can be further classified as Homogeneous and Heterogeneous.
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Heat is released.
When a chemical change occurs, energy comes out of the atoms which causes heat.
2 correct answers: Chemical and neither endothermic or exothermic