Final answer:
In the chlorate ion (ClO₃⁻), the oxidation state of chlorine (Cl) is +5 and the oxidation state of oxygen (O) is -2.
Step-by-step explanation:
For the chlorate ion (ClO₃⁻), we need to determine the oxidation states of chlorine (Cl) and oxygen (O) respectively. Oxygen typically has an oxidation state of -2. Since the chlorate ion has a charge of -1 and consists of one chlorine atom and three oxygen atoms, the sum of the oxidation states of all the atoms must equal -1 (the charge of the ion).
Applying the rules to find the oxidation state of chlorine:
3 (oxidation state of O) + (oxidation state of Cl) = -1
3 (-2) + (oxidation state of Cl) = -1
-6 + (oxidation state of Cl) = -1
(oxidation state of Cl) = +5
Therefore, the oxidation state of Cl in ClO₃⁻ is +5, and the oxidation state for each oxygen is -2.