In acidic medium,$H_2O_2$ changes $Cr_2O_7^{2-}$ to $CrO_5$ which has two peroxy linkages. The oxidation state of $Cr$ in $CrO_5$ is

Find out the oxidation number of chlorine in the following compounds and arrange them in increasing order of oxidation number of chlorine.
$NaClO_4, NaClO_3, NaClO, KClO_2, Cl_2O_7, ClO_3, Cl_2O, NaCl, Cl_2, ClO_2$.
Which oxidation state is not present in any of the above compounds?

When ammonium nitrate is heated rapidly,an oxide of nitrogen is formed. What is the oxidation state of nitrogen in this oxide?

What is the change in oxidation number of $S$ in the following reaction?
$H_2S + NO_3^- \longrightarrow H_2O + NO + S$

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

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