Question

match the vocabulary terms with their definitions. smallest unit of a chemical element a. atom b. galaxy substance composed of one type of atom c. gravity d. element a group of solar systems, dust, and gas held together by gravity

Explanation:

An atom is the smallest unit of a chemical element. An element is a substance composed of one - type of atom. A galaxy is a group of solar systems, dust, and gas held together by gravity.

Answer:

smallest unit of a chemical element - a. atom
substance composed of one type of atom - d. element
a group of solar systems, dust, and gas held together by gravity - b. galaxy