Question

13. Contrast endothermic and exothermic reactions (Unit 1).

Answer 1

13). Atoms are the basic unit of matter

14). Elements (pure substances, one type of atom) and Compound (made up of two or more types of atoms)

16). Chemical change

17). If a rock is changed or broken and stays where it is, it is weathering. If pieces of pebbles and soil from the rock are moved by natural forces, it is erosion

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