In chloro-alkali industries,during the Solvay ammonia process,a redox change occurs during:

$6 \times 10^{-3} \text{ mole}$ of $K_2Cr_2O_7$ reacts completely with $9 \times 10^{-3} \text{ mole}$ of $X^{n+}$ to give $XO_3^-$ and $Cr^{3+}$. The value of $n$ is:

The gaseous product of the reaction between $Sn$ and conc. $H_2SO_4$ is

Consider the reactions:
$(a)$ $6 CO_{2(g)} + 6 H_{2}O_{(l)} \rightarrow C_{6}H_{12}O_{6(aq)} + 6 O_{2(g)}$
$(b)$ $O_{3(g)} + H_{2}O_{2(l)} \rightarrow H_{2}O_{(l)} + 2 O_{2(g)}$
Why is it more appropriate to write these reactions as:
$(a)$ $6 CO_{2(g)} + 12 H_{2}O_{(l)} \rightarrow C_{6}H_{12}O_{6(aq)} + 6 H_{2}O_{(l)} + 6 O_{2(g)}$
$(b)$ $O_{3(g)} + H_{2}O_{2(l)} \rightarrow H_{2}O_{(l)} + O_{2(g)} + O_{2(g)}$
Also,suggest a technique to investigate the path of the above $(a)$ and $(b)$ redox reactions.

In the reaction between moist $SO_2$ and acidified permanganate solution:

Which of the following act as an oxidising as well as a reducing agent?