$H_2O_2$ reduces $K_4[Fe(CN)_6]$ in which of the following conditions?

The normality of $20$ volume solution of hydrogen peroxide is (in $N$)

The chemical nature of hydrogen peroxide is

Rohan heard that instructions were given to the laboratory attendant to store a particular chemical,i.e.,keep it in the dark room,add some urea in it,and keep it away from dust. This chemical acts as an oxidising as well as a reducing agent in both acidic and alkaline media. This chemical is important for use in the pollution control treatment of domestic and industrial effluents.
$(i)$ Write the name of this compound.
$(ii)$ Explain why such precautions are taken for storing this chemical.

The reaction of $H_{2}O_{2}$ with potassium permanganate in acidic medium leads to the formation of mainly.

$I. \, H_2O_2 + O_3 \rightarrow H_2O + 2O_2$
$II. \, H_2O_2 + Ag_2O \rightarrow 2Ag + H_2O + O_2$
The role of hydrogen peroxide in the above reactions is respectively: