In the conversion $Br_2 \to BrO_3^-$,the oxidation state of bromine changes from

$A, B,$ and $C$ are three elements forming a compound in which their oxidation states are $+2, +5,$ and $-2$ respectively. If the compound is neutral,which of the following represents the formula of the compound?

The oxidation states of $P$ in $PO_4^{3-}$,$S$ in $SO_4^{2-}$,and $Cr$ in $Cr_2O_7^{2-}$ are respectively:

Assign oxidation number to the underlined elements in each of the following species:
$(a)$ $NaH_2\underline{P}O_4$
$(b)$ $NaH\underline{S}O_4$
$(c)$ $H_4\underline{P_2}O_7$
$(d)$ $K_2\underline{Mn}O_4$
$(e)$ $Ca\underline{O_2}$
$(f)$ $Na\underline{B}H_4$
$(g)$ $H_2\underline{S_2}O_7$
$(h)$ $KAl(\underline{S}O_4)_2 \cdot 12H_2O$

In chromite ore,the oxidation number of iron and chromium are respectively

The correct set of oxidation numbers of $Br$ in $Br_3O_8$ is