4 what is the simplest form of matter composed of only one type of atom? a element b compound c mixture d…

Brief Explanations:

Elements are the simplest form of matter made up of only one - type of atom. Compounds consist of two or more different types of atoms chemically bonded. Mixtures are combinations of different substances that are not chemically combined. Colloids are a type of mixture with dispersed particles.

Answer:

A. Element