Which of the following liberates $O_2$ upon hydrolysis?

$1 \ mL$ of "$x$ volume" $H_2O_2$ solution on heating gives $20 \ mL$ of oxygen gas at $STP$. The $(w/v) \%$ corresponding to "$x$ volume" of $H_2O_2$ is

The compound which does not possess a peroxide linkage is

$A$ compound $(MO_2)$ of a group $1$ element $(M)$ is hydrolyzed to form $M^{+}$,$OH^{-}$,$X$,and $Y$. When $X$ reacts with $I_2$ in a basic medium,the products formed are $I^{-}$,water,and $Y$. Then $X$ and $Y$ are respectively:

The normality of $20$ volume solution of hydrogen peroxide is (in $N$)

Which of the following compounds is a peroxide?