Consider the figure below, in which the blue circles represent atoms of copper metal, atomic mass 63.5 amu, while the red circles represent atoms in zinc metal, atomic mass 65.4 amu.
Here are four statements concerning this system. Identify the correct statement or statements.
I. This is a single-phase mixture, with a copper-to-zinc atom ratio of 3:1.
II. This is two-phase mixture, with a copper-to-zinc atom ratio of 8:1.
III. The mixture is 80% copper, by mass.
IV. This mixture could be an alloy of copper and zinc.