Answer
A. $NI_3$ -> molecule
B. copper metal -> atoms
C. $SrCl_2$ -> formula units
D. nitrogen -> diatomic molecules
Work Step by Step
Nitrogen is diatomic, meaning its atoms naturally bond with itself to form molecules. $NI_3$ is a molecule, where different types of atoms bond together covalently. $SrCl_2$ represents a formula unit, the lowest whole number ratio of ions in a compound.
