Final answer:
The first formula, C2H4S, cannot be reduced further and is the empirical formula, as it represents the simplest whole-number ratio of elements in the compound.
Step-by-step explanation:
To determine which of the following chemical formulas represents an empirical formula, we should look for the simplest whole-number ratio of atoms in the compound. The empirical formula of a molecule is the simplest ratio of the elements that make up the compound. An empirical formula does not necessarily represent the actual number of atoms in a molecule, but rather the simplest ratio in which the atoms combine.
Considering the two formulas provided, C2H4S and C2H4S2, the second formula has sulfur atoms that can be simplified (the ratio of C:H:S can be reduced to 1:2:1, becoming CH2S). Therefore, the first formula, C2H4S, is already in its simplest form and cannot be reduced further, making it the empirical formula for the compound. It represents the lowest whole-number ratio of elements in the compound.