Consider a hypothetical element $\mathrm{M},$ which is capable of forming stable simple cations that have charges of $1+, 2+,$ and $3+,$ respectively. Write the formulas of the compounds formed by the various $M$ cations with each of the following anions.
a. chromate
b. dichromate
c. sulfide
d. bromide
e. bicarbonate
f. hydrogen phosphate