The oxidation state of iodine in $I_3^{-}$ is:

$A$ compound contains three elements $A$,$B$,and $C$. If the oxidation numbers are $A = +2$,$B = +5$,and $C = -2$,the possible formula of the compound is:

What is the oxidation state of $As$ in $H_{3}AsO_{4}$?

The oxidation states of $S$ in $H_2S_2O_7$ are:

What is the oxidation state of phosphorus in the phosphate ion $(PO_4^{3-})$?

What is the change in the oxidation number of nitrogen when $NO_3^{-}$ is converted to $NH_4^{+}$ ion?