How many peroxide groups are present in $CrO_5$?

The oxidation states of $S$ in Peroxodisulphuric acid $(H_2S_2O_8)$ and Sodium tetrathionate $(Na_2S_4O_6)$ are respectively:

The oxidation numbers of $As$ are

The oxidation states of sulphur in the anions $SO_3^{2-}$,$S_2O_4^{2-}$ and $S_2O_6^{2-}$ follow the order:

What is the oxidation state of chlorine atom in chloric acid?

Compounds having the highest oxidation state of the central atom act as acids,the lowest ones act as bases,and intermediate oxidation states act as amphoteric. Which one of the following is amphoteric?