Which one of the following is reduced by hydrogen peroxide in acid medium?

Which of the following oxides will produce hydrogen peroxide upon reaction with dilute acid?

Which of the following products are formed on the hydrolysis of $NaO_2$?

$KO_2$ reacts with water to form $A$,$B$ and $C$. $B$ forms $C$ when it reacts with iodine in basic medium. What are $B$ and $C$ respectively?

The correct statements from the following are:
$i$. $Ca(OH)_2$ is used in Clark's method of removal of temporary hardness of water.
$ii$. $100 \ mL$ of $10$ vol $H_2O_2$ on complete decomposition liberates $1 \ L$ of oxygen at $STP$.
$iii$. Urea can be added to the solution of $H_2O_2$ as stabilizer.

$H_2O_2$ is a hydride of