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

What is the oxidation number of $Mn$ in $MnO_4^{-}$?

Oxidation numbers of $P$ in $PO_4^{3-}$,of $S$ in $SO_4^{2-}$ and that of $Cr$ in $Cr_2O_7^{2-}$ are respectively

What is the oxidation number of carbon in $K_2C_2O_4$?

What is the oxidation state of osmium $(Os)$ in $OsO_4$?

When $KMnO_4$ acts as an oxidising agent and ultimately forms $[MnO_4]^{2-}$,$MnO_2$,$Mn_2O_3$,and $Mn^{2+}$,the number of electrons transferred in each case respectively is: