Addition of $H_{2}SO_{4}$ to $BaO_{2}$ produces

Which of the following oxides produces $H_2O_2$ when treated with $HCl$?

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.

In $H_2O_2$,the two oxygen atoms are connected by:

Electrolysis of $X$ gives $Y$ at anode. Vacuum distillation of $Y$ gives $H_2O_2$. The number of peroxy $(O-O)$ bonds present in $X$ and $Y$ respectively are :

The oxidation states of the most electronegative element in the products of the reaction of $BaO_2$ with dilute $H_2SO_4$ are