The equation $H_2S + H_2O_2 \to S + 2H_2O$ represents:

In which of the following reactions does $H_2O_2$ act as an oxidising agent (either in acidic,alkaline,or neutral medium)?
$(i)$ $2Fe^{2+} + H_2O_2 \rightarrow$
$(ii)$ $2MnO_4^{-} + 6H^{+} + 5H_2O_2 \rightarrow$
$(iii)$ $I_2 + H_2O_2 + 2OH^{-} \rightarrow$
$(iv)$ $Mn^{2+} + H_2O_2 \rightarrow$

The compound that can work both as an oxidising and reducing agent is

$A$ : The $O-O$ bond length in $H_2O_2$ is smaller than that in $O_2F_2$.
$R$ : $H_2O_2$ is an ionic compound.

Assertion: Sulfur is oxidized by $H_2O_2$ in the presence of $Fe(III)$.
Reason: $Fe(III)$ catalyzes the oxidation of sulfur to sulfate.

The volume strength of $1 \, M \, H_2O_2$ is : (Molar mass of $H_2O_2 = 34 \, g \, mol^{-1}$)