AP Chemistryeasymcq1 pt
What is the oxidation number of chlorine in the chlorate ion, ClO₃⁻?
A.+5
B.+7
C.-1
D.0
Explanation
Core Concept
Three oxygens contribute a combined -6. Because the whole ion carries a charge of -1, chlorine must supply +5 so the assignments sum to the ionic charge: x + 3(-2) = -1. For polyatomic ions the oxidation numbers total the ion's charge rather than zero, which is the key adjustment from neutral-molecule practice.
Correct Answer
A+5
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