Question

which of the following is not an element?
a copper (cu)
b carbon (c)
c chlorine (cl)
d water (h₂o)

Explanation:

An element is a pure substance that cannot be broken down into simpler substances. Copper (Cu), carbon (C), and chlorine (Cl) are elements. Water (H₂O) is a compound made of hydrogen and oxygen atoms.

Answer:

d. water (H₂O)