Question

what is the oxidation number of chlorine

Answer 1

Chlorine gas has on oxidation number of zero

Chlorine in compounds with other elements usually has an oxidation number of -1, except in compounds with O or F (see below)

Chlorine in compounds with fluorine or oxygen:-

There are so many different oxidation states that chlorine can have in these, that it is safer to simply remember that the chlorine doesn't have an oxidation state of -1 in them, and work out its actual oxidation state when you need it.

Answer 2

hii
-1 is the oxidation number of chlorine.
thnx