Chapter 3 - Section 3.3 - Representing Compounds: Chemical Formulas and Molecular Models - For Practice - Page 91: 3.1

a) $C_5H_{12}$ b) $HgCl$ c)$CH_2O$

To obtain the empirical formula, we divide the subscripts by their greatest common factor. a) for $C_5H_{12}$, the greatest common factor of the subscripts is 1. Thus, the empirical formula is $C_5H_{12}$ b) for $Hg_2Cl_{2}$, the greatest common factor of the subscripts is 2. So, the empirical formula is $HgCl$ c) for $C_2H_4O_{2}$, the greatest common factor of the subscripts is 2. So, the empirical formula is $CH_2O$