Textbook Problem

Name the following binary ionic compounds, using a Roman numeral to indicate the charge on the metal ion:

a. ${\text{CrCl}}_2$ and ${\text{CrCl}}_3$

b. $\text{CoS}$ and ${\text{Co}}_{\text{2}}{\text{S}}_{\text{3}}$

c. $\text{FeO}$ and ${\text{Fe}}_{\text{2}}{\text{O}}_{\text{3}}$

d. ${\text{PbCl}}_2$ and ${\text{PbCl}}_4$