What is the oxidation number of cl in chlorate ion clo3?

The correct answer to this question is "5." the oxidation number of cl in ClO3 will be a positive 5 because oxygen is naturally a -2 charge. times that by three and then account for the negative charge of the CLO3- ion.

Answer is: the oxidation number of Cl (chlorine) in chlorate ion is +5.

Chlorate ion (ClO₃⁻) has negative charge.

One oxygen atom in this anion (negatively charged ion) has the oxidation number -2. There are three oxygen atoms in chlorate anion.

x + 3 · (-2) = -1.

x = -1 + 6.

x = +5; the oxidation number of chlorine.