The oxidation state of $Cr$ in $Cr_2O_7^{2-}$ 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:

Assign the oxidation number to the underlined element in each of the following species:
$1$. $NaH_{2}\underline{P}O_{4}$
$2$. $NaH\underline{S}O_{4}$
$3$. $H_{4}\underline{P_{2}}O_{7}$

What is the oxidation number of $Xe$ in $Ba_2XeO_6$?

What is the oxidation state of oxygen in $OF_2$?

An acidic solution of sodium thiosulfate is unstable because in thiosulfate,the two sulfur atoms have different oxidation states of: