Which is the correct order of stability for the given oxygen species?

When $CO_2$ is bubbled through a solution of barium peroxide in water:

Blackened oil painting can be restored into original form by the action of :

There is a sample of $10$ volume of hydrogen peroxide solution. Calculate its strength in percentage (%).

With reference to the redox properties of hydrogen peroxide $(H_2O_2)$,which of these reactions are feasible?
$(I)$ $2Fe^{2+} + 2H^{+} + H_2O_2 \longrightarrow 2Fe^{3+} + 2H_2O$
$(II)$ $2MnO_4^{-} + 6H^{+} + 5H_2O_2 \longrightarrow 2Mn^{2+} + 8H_2O + 5O_2$
$(III)$ $2Fe^{2+} + H_2O_2 \longrightarrow 2Fe^{3+} + 2OH^{-}$
$(IV)$ $2MnO_4^{-} + 3H_2O_2 \longrightarrow 2MnO_2 + 2H_2O + 3O_2 + 2OH^{-}$

What is the amount of $H_2O_2$ in grams present in $1 \ L$ of $1.5 \ N$ $H_2O_2$ solution?