Question

A substance that forms when two or more elements join chemically is

A.an ion
B.compound
C. A formula
D. An atom

Answer 1

That would be a compound.

Answer 2

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.