Answer
a.) Mercury (I) Oxide
b.) Iron (III) Bromide
c.) Cobalt (II) Sulfide
d.) Titanium (IV) Chloride
e.) $Sn_3N_2$
f.) $CoI_3$
g.) $HgO$
h.) $CrS_3$
Work Step by Step
All of these compounds are ionic compounds (composed of a cation and an anion (usually a non-metal and a metal)) so no Greek prefixes need to be added to the beginning of any element names. Since all of these compounds contain transition metals, a roman numeral must be included when naming that certain transition metal. These roman numerals denote the magnitude of the positive charge of the ion. It will always be a positive charge.
a.) $Hg_2O$ can be split up into $2Hg^{+} + O^{2-}$
= Mercury (I) Oxide
b.) $FeBr_3$ can be split up into $Fe^{3+} + 3Br^{-}$
= Iron (III) Bromide
c.) $CoS$ can be split up into $Co^{2+} + S^{2-}$
= Cobalt (II) Sulfide
d.) $TiCl_4$ can be split up into $Ti^{4+} + 4Cl^{-}$
= Titanium (IV) Chloride
e.) Tin (II) is $Sn^{2+}$ and nitride corresponds to nitrogen which is $N^{3-}$
= $Sn_3N_2$
f.) Cobalt (III) is $Co^{3+}$ and iodide corresponds to iodine which is $I^{-}$
= $CoI_3$
g.) Mercury (II) is $Hg^{2+}$ and oxide corresponds to oxygen which is $O^{2-}$
= $HgO$
h.) Chromium (VI) is $Cr^{6+}$ and sulfide corresponds to sulfur which is $S^{2-}$
= $CrS_3$
