Q: What is the oxidation number of chlorine in ClO3-?

What is the oxidation number of chlorine in ClO3-?

Flexi Says: Halogens (Cl, Br, I) have negative oxidation numbers when they form halide compounds. When combined with oxygen, they have positive numbers. In the chlorate ion (ClO3-), the oxidation number of Cl +5, and the oxidation number of O is -2.