Question

drag the missing word into place a(n) of carbon dioxide contains one carbon atom and two oxygen atoms. molecule energy solid

Explanation:

A molecule is the smallest unit of a compound that retains its chemical properties. Carbon dioxide ($CO_2$) is composed of one carbon atom and two oxygen atoms bonded together, which fits the definition of a molecule. "Energy" refers to the capacity to do work and is not a physical entity like $CO_2$. "Solid" is a state of matter, not a unit of a compound's structure.

Answer:

molecule