$A$ colourless liquid $A$ contains $H$ and $O$ elements only. It decomposes slowly on exposure to light. It is stabilised by mixing urea to store in the presence of light.
$(i)$ Suggest the possible structure of $A$.
$(ii)$ Write the chemical equation for its decomposition reaction in light.

In the reaction of $BaO_2$ with dilute $H_2SO_4$,what are the oxidation states of the most electronegative element in the products?

Fill in the blanks:
$(1)$ $H_2O_2$ acts as an antiseptic, then it is known as ......... in the market.
$(2)$ Cation exchange resin is a ......... group containing organic molecule.
$(3)$ The ionic radius of $H^+$ ions and that of other ions is ......... $pm$ and ......... $pm$ respectively.
$(4)$ ......... group elements give salt-like hydrides.

What is the $\%$ strength of $22.4$ volume of $H_2O_2$ solution (in $\%$)?

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

Which one of the following reactions indicates the reducing ability of hydrogen peroxide in basic medium?