In which of the following is a peroxy bond present?

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.

Which of the following is incorrect regarding $H_2O_2$?

The bond angle $H-O-O$ in $H_2O_2$ in the gaseous phase is (in $^{\circ}$)

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

$H_2O_2$ is manufactured these days by