The formal oxidation numbers of $Cr$ and $Cl$ in the ions $Cr_2O_7^{2-}$ and $ClO_3^{-}$ respectively are

What are the oxidation numbers of nitrogen in $NH_4NO_3$?

What is the oxidation number of the oxygen atom in the $O_2^{2-}$ ion?

One mole of $N_2H_4$ loses $10 \ mol$ of electrons to form a new compound $Y$. Assuming that all nitrogen atoms appear in the new compound,what is the oxidation state of $N$ in $Y$? (There is no change in the oxidation state of hydrogen)

Match the following compounds with their respective oxidation numbers of the central atom or specific element:

Compound	Oxidation number
$1$. $C_2H_6$	$a$. $+3$
$2$. $H_2O_2$	$b$. $+6$
$3$. $LiAlH_4$	$c$. $-3$
$4$. $HO_2^-$	$d$. $-1$
$5$. $PbSO_4$	$e$. $+1$

The order of the oxidation state of the phosphorus atom in $H_3PO_2$,$H_3PO_4$,$H_3PO_3$,and $H_4P_2O_6$ is: