In which of the following reactions does ${\mathrm{H}}_2{\mathrm{O}}_2$ act as a reducing agent?

The reactions in which ${\mathrm{H}}_2{\mathrm{O}}_2$ acts as a reducing agent is,

${\mathrm{Cl}}_2+{\mathrm{H}}_2{\mathrm{O}}_2⟶2\mathrm{HCl}+{\mathrm{O}}_2$

Both oxidizing and reducing  ${\mathrm{H}}_2{\mathrm{O}}_2$ to ${\mathrm{H}}_2{\mathrm{O}}_2$ are possible. Consequently, it can function as an oxidising  agent by itself by becoming reduced to ${\mathrm{H}}_2\mathrm{O}$  and a reducing agent by becoming oxidised to ${\mathrm{O}}_2$ . As a result, it has the ability to operate as an oxidizing and reducing agent. The reaction is having follows

${\mathrm{H}}_2^{-1}{\mathrm{O}}_2\to {\mathrm{H}}_2^{-2}\mathrm{O}+{\mathrm{O}}_2^0$