What is the oxidation number of $N$ in $NH_2-NH_2$?

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

Fill in the blanks:
$(1)$ Oxidation number of $Cr$ in $Na_3Cr_3O_{10}$ is ........
$(2)$ Oxidation number of $H$ in lithium aluminum hydride $(LiAlH_4)$ is .......
$(3)$ Oxidation number of oxygen in potassium ozonide $(KO_3)$ is .........
$(4)$ Oxidation number of $C$ in fullerene and graphite is .......

What is the oxidation number of $S$ in $H_2SO_4$?

In which of the following, the oxidation state of nitrogen is lowest?

When $KMnO_4$ is reduced with oxalic acid in acidic solution,the oxidation number of $Mn$ changes from