Question

An element is composed of

Answer 1

All the same atoms, i.e. oxygen, O2 is an element as all the atoms are oxygen atoms. H2O is not an element as there are H atoms and an O atom.

Answer 2

An element is composed of atoms which are actually the simplest particles of an element.

Answer 3

A group of similar ATOMS is known as element.

Answer 4

Not just similar atoms @Arshadaliawan... It's identical atoms with the exact same number of protons. A pure substance made up of only one type of atom. The only mass variations allowed are in the number of electrons (called ions of that element) and neutrons (called isotopes of that element).