When $H_{2}O_{2}$ is shaken with an acidified solution of $K_{2}Cr_{2}O_{7}$ in the presence of ether, the ethereal layer turns blue due to the formation of

The species that is not hydrolysed in water is

Describe the structure of hydrogen peroxide $(H_2O_2)$.

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 $pH$ of an $H_2O_2$ solution is $6$. If some chlorine gas is passed through it,which of the following statements is correct?

Assertion $(A)$: The colour of old lead paintings can be restored by washing them with a dilute solution of $H_2O_2$.
Reason $(R)$: Hydrogen peroxide reduces $PbS$ to $Pb$.