What is the oxidation number of $Cl$ in $HClO_4$ and $HClO_3$?

What is the change in the oxidation state of $Mn$ in the reaction of $MnO_4^{-}$ with $H_2O_2$ in acidic medium?

In which of the following oxoacids of phosphorus is the oxidation state of phosphorus the minimum?

The oxidation number of $C$ atom in $CH_{2}Cl_{2}$ and $CCl_{4}$ are respectively:

$A$ compound contains atoms $X$,$Y$,and $Z$. The oxidation number of $X$ is $+2$,$Y$ is $+5$ and $Z$ is $-2$. Therefore,a possible formula of the compound is

The oxidation state of $Cr$ in $CrO_6$ is