Find the valences of the underlined elements or radicals in the following compounds.
$\underset{\_}{\mathrm{B}\mathrm{a}}\mathrm{C}{\mathrm{l}}_2,\underset{\_}{ \mathrm{P}}\mathrm{C}{\mathrm{l}}_3, \underset{\_}{\mathrm{P}}\mathrm{C}{\mathrm{l}}_5, \underset{\_}{\mathrm{N}}{\mathrm{H}}_3, \mathrm{M}\mathrm{g}\underset{\_}{\mathrm{S}{\mathrm{O}}_4}, \mathrm{C}\mathrm{a}\underset{\_}{\mathrm{C}{\mathrm{O}}_3}, \underset{\_}{\mathrm{N}{\mathrm{a}}_2}\mathrm{O}, \underset{\_}{\mathrm{C}\mathrm{a}}\mathrm{O},\underset{\_}{ \mathrm{C}\mathrm{a}}{\left(\mathrm{O}\mathrm{H}\right)}_2,\underset{\_}{ \mathrm{F}\mathrm{e}}\mathrm{S}{\mathrm{O}}_4,$
$\underset{\_}{\mathrm{F}\mathrm{e}}\mathrm{C}{\mathrm{l}}_3,\underset{\_}{ \mathrm{F}{\mathrm{e}}_2}{\mathrm{O}}_3, \mathrm{N}\mathrm{a}\underset{\_}{\mathrm{O}\mathrm{H}}, \underset{\_}{\mathrm{A}\mathrm{l}}{\left(\mathrm{O}\mathrm{H}\right)}_3,\underset{\_}{ \mathrm{N}{\mathrm{a}}_2}\mathrm{C}{\mathrm{o}}_3$