What is the gas liberated when alkaline formaldehyde solution is treated with $H_2 O_2$?

How does $H_{2}O_{2}$ behave as a bleaching agent?

What is the approximate volume (in $mL$) of $10$ vol $H_2O_2$ solution that will react completely with $1 \ L$ of $0.02 \ M \ KMnO_4$ solution in acidic medium?

Given below are two statements:
Statement $I$: $H_{2}O_{2}$ can act as both an oxidising and a reducing agent in a basic medium.
Statement $II$: In the hydrogen economy,the energy is transmitted in the form of dihydrogen.
In the light of the above statements,choose the correct answer from the options given below:

$H_2O_2$ is manufactured these days by

Reaction $H_2S_2O_{8(aq)} \xrightarrow{H_2O} 2H_2SO_4 + x.$ What is product $x$?