What are the oxidation numbers of S atoms in $$\mathrm{S}_4 \mathrm{O}_6^{2-}$$ ?

How many grams of Mg is required to completely reduce $$100 \mathrm{~mL}, 0.1 \mathrm{~M} \mathrm{~NO}_3^{-}$$ solution using the following reaction?

$$\mathrm{NO}_3^{-}+\mathrm{Mg} \longrightarrow \mathrm{Mg}^{2+}+\mathrm{NH}_3$$

What is the oxidation state of S in the sulphur containing product of the following reaction?

$$\mathrm{SO}_3^{2-}(a q)+\mathrm{Br}_2(l)+\mathrm{H}_2 \mathrm{O} \longrightarrow$$

In the reaction of phosphorus with conc. $$\mathrm{HNO}_3$$, the oxidised and reduced products respectively are