Write the empirical formula for each of the following substances:
a. $\mathrm{C}_{6} \mathrm{H}_{6} \mathrm{O}_{3}$, pyrogallol, a developer in photography
b. $\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}$, galactose, a carbohydrate
c. $\mathrm{C}_{8} \mathrm{H}_{6} \mathrm{O}_{4}$, terephthalic acid, used in the manufacture of plastic bottles
d. $\mathrm{C}_{6} \mathrm{Cl}_{6}$, hexachlorobenzene, a fungicide
e. $\mathrm{C}_{24} \mathrm{H}_{16} \mathrm{O}_{12}$, laccaic acid, a crimson dye