Which of the following are phase changes? (Select all that apply.) melting
gases
sublimation
reactions

- melting

- sublimation

Explanation:

A phase change is a, well, change between phases. Solid to liquid. Gas to solid. Etc. Gases is a phase, but not a change. Reactions is a change, but not a phase change. This leaves us with melting (solid to liquid) and sublimation (solid to gas).

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- Heather

every chemical equation adheres to the law of conservation of mass, which states that matter cannot be created or destroyed. therefore, there must be the same number of atoms of each element on each side of a chemical equation.

each chemical family is represented as a group or column on the periodic table. based on chemical properties, there are 6 types of chemical families. group 1 represents alkali metals, group 2 represents alkaline earth metals, groups 3 to 12 represent transition metals, groups 13 to 16 represent non-metals and other metals, group 17 represents halogens and group 18 represents noble gases.