What are the oxidation states of $S$ in $S_8$,$H_2S$,and $S_2F_2$ respectively?

The oxidation number of phosphorus in $Ba(H_2PO_2)_2$ 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:

$A$ compound contains atoms of three elements $A$,$B$ and $C$. If the oxidation number of $A$ is $+2$,$B$ is $+5$ and that of $C$ is $-2$,the possible formula of the compound is:

An acidified solution of sodium thiosulfate is unstable because in thiosulfate,the two sulfur atoms are in:

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