Asubstance that forms when two or more elements join chemically is a. an ion b. compound c. a formula d. an atom

When two or more elements join together chemically, we have a B. compound.

Water is a compound because of its molecular formula H2O

There are 2 atoms of hydrogen and 1 atom of oxygen bonded together.

firearm identification is the process of analyzing the bullets and cartridge cases left at a crime scene to determine if they came from a particular firearm. marks on the bullets and cartridges may be common to every firearm of that type. these are called class characteristics.