$6.8 \, g$ of $H_2O_2$ is dissolved in $0.2 \, L$ of solution. Then the solution will be labelled as ............. $V$ volume strength.

The correct statements among the following are
$i$. Saline hydrides produce $H_2$ gas when reacted with water
$ii$. Presently $\sim 77 \%$ of the industrial dihydrogen is produced from coal
$iii$. Commercially marketed $H_2O_2$ contains $3 \% H_2O_2$

$H_2O_2$ is used as:

The $pH$ of a solution of $H_2O_2$ is $6.0$. Some chlorine gas is bubbled into this solution. Which of the following is correct?

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.

$20$ volume $H_2O_2$ solution has a strength of about $........... \%$