Question

what is the difference between oxidation state and oxidation no. and why is it that oxidation state can be fractional while oxidation no. is always a whole no.

Answer 1

Broadly speaking the terms oxidation state and oxidation number are often used interchangeably and there is as such no difference between the two. Oxidation state is the degree of oxidation that is the charge on a species. Oxidation number more or less represents the same thing, however the latter is used in coordination compounds.