Which option describes a molecule? A. the basic unit of matter
B. a substance that is formed when two or more atoms join
C. a pure substance that is formed when atoms of different elements come together
D. a physical substance that takes up space and has mass

Some molecular compounds, such as hcl, ionize completely in solution. for molecular compounds such as h2co3, most molecules do not ionize in solution. which describes the properties of these two solutes? a. hcl and h2co3 have the same effect on the properties of the solution. b. hcl raises the freezing point of water more than h2co3 does. c. hcl raises the boiling point of water more than h2co3 does.