Final answer:
The chemical formula P₄O₁₀ is not an empirical formula because it can be reduced to a simpler whole-number ratio, P₂O₅, which is its empirical formula.
Step-by-step explanation:
The chemical formula that is not an empirical formula among the options provided is P₄O₁₀. An empirical formula represents the simplest whole-number ratio of elements in a compound. P₄O₁₀, which is also known as phosphorus pentoxide, is the molecular formula and can be reduced to its empirical formula, P₂O₅. The options 8H₂O and C₄H₆O₃ are not empirical formulas either, as their subscripts can be reduced to simplified ratios (for example, 8H₂O can be simplified to H₂O). In contrast, BaCl₂ and K₂S are already in their simplest whole-number ratios and thus represent empirical formulas.