Peroxomonosulfuric acid $H X_{2} SO X_{5}$ has the structure $HO - SO X_{2} - O - OH$ (S bonded to two oxo O, one OH and one OOH group). Take H as $+ 1$ , O as $- 1$ in the O-O linkage and $- 2$ elsewhere. The oxidation number of S and the number of O atoms with oxidation number $- 1$ are

Answer: A

Charge balance:

2 (+ 1) + x + 2 (- 1) + 3 (- 2) = 0

gives

x = + 6

(two peroxo O at

- 1

, three other O at

- 2

). Ignoring the peroxo link would give an impossible

+ 8