What is the volume strength of $3.0 \, N$ $H_2O_2$ solution in liters?

$H_2O_2$ is manufactured these days by:

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.

There is a sample of $10$ volume of hydrogen peroxide solution. Calculate its strength in percentage (%).

By which of the following methods,$H_2O_2$ cannot be synthesized?

The volume strength of perhydrol is