On shaking $H_2O_2$ with acidified potassium dichromate and ether,the ethereal layer becomes:

Hydrolysis of one mole of peroxodisulphuric acid $(H_2S_2O_8)$ yields:

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 :

$(i)$ Give a method for the manufacture of hydrogen peroxide and explain the reactions involved therein.
$(ii)$ Illustrate oxidising,reducing and acidic properties of hydrogen peroxide with equations.

The $K_a$ of $H_2O_2$ is of the order of:

Which substance does not speed up the decomposition of $H_2O_2$?