In polythionic acid, ${\mathrm{H}}_2{\mathrm{ }\mathrm{S}}_x{\mathrm{O}}_6(x=3$ to 5) the oxidation state(s) of sulphur is/are:

 Polythionic acid is an oxoacid which has a straight chain of sulfur atoms and has the chemical formula ${\mathrm{S}}_n{\left({\mathrm{SO}}_3\mathrm{H}\right)}_2(n>2)$

For ${\mathrm{H}}_2{\mathrm{ }\mathrm{S}}_x{\mathrm{O}}_6$ ( $x=3$ to 5 ), there are two polythionic acids possible, i.e., trithionic acid $\left({\mathrm{H}}_2{\mathrm{ }\mathrm{S}}_3{\mathrm{O}}_6\right)$ having oxidation number 0 and tetrathionic acid $\left({\mathrm{H}}_2{\mathrm{ }\mathrm{S}}_4{\mathrm{O}}_6\right)$ having oxidation number +5.