The oxidation state of phosphorus in hypophosphoric acid is $+......$

Sulphur in $+3$ oxidation state is present in

The oxidation numbers of sulphur in $S_8$,$S_2F_2$,and $H_2S$ respectively,are:

In the chromyl chloride test for the confirmation of $Cl^{-}$ ion,a yellow solution is obtained. Acidification of the solution and the addition of amyl alcohol and $10\% H_2O_2$ turns the organic layer blue,indicating the formation of chromium pentoxide. The oxidation state of chromium in that compound is:

The oxidation state of $Fe$ in $Fe_3O_4$ is:

What are the oxidation states of phosphorus in the following:
$(i)$ $H_{3}PO_{3}$
$(ii)$ $PCl_{3}$
$(iii)$ $Ca_{3}P_{2}$
$(iv)$ $Na_{3}PO_{4}$
$(v)$ $POF_{3}$