Question

What is an element?
A.
a substance made up of hydrogen and one other kind of atom
B.
a substance made of just one kind of molecule that cannot be broken down into something simpler
C.
a substance made of just one kind of atom that cannot be broken down into something simpler
D.
a material that is shiny and usually hard and strong

Answer 1

C

An element is a substance made of only one kind of atom and cannot be chemically broken down into simpler substances. (A describes a compound, B misuses "molecule," and D describes metals, not elements in general.)