Identify reductant in following reaction.

$$\mathrm{H}_2 \mathrm{~S}+\mathrm{NO}_2 \rightarrow \mathrm{H}_2 \mathrm{O}+\mathrm{NO}+\mathrm{S}$$

Oxidation state of Cr in potassium dichromate is

What is the value of '$$\mathrm{x}$$' in order to balance the following redox reaction by ion electron method? $$\quad \mathrm{x} \mathrm{H}_2 \mathrm{O}_2+\mathrm{ClO}_4 \rightarrow \mathrm{xO}_2+\mathrm{ClO}_2+2 \mathrm{H}_2 \mathrm{O}$$

Identify reductant in following reaction.

$$\mathrm{{C_2}O_4^{2 - } + MnO_4^ - + {H^ + } \longrightarrow M{n^{2 + }} + C{O_2} + {H_2}O}$$