Final answer:
The correct chemical formula for potassium chlorate is KClO₃ (option a).
Step-by-step explanation:
The correct chemical formula for potassium chlorate is KClO₃ (option a). It consists of one potassium ion (K⁺), one chloride ion (Cl⁻), and three oxygen ions (O²⁻) in the ratio of 1:1:3. The formula is derived from the charges of the ions and the principle of charge balance in compounds.