Which of the following substances acts as an oxidising as well as a reducing agent?

In the following reaction,assign the oxidation state for the underlined atom in the products of complete hydrolysis at $R.T.$:
$H_2\underline{S}_2O_6 + H_2O \longrightarrow H_2SO_3 + H_2SO_4$

Assign $A, B, C, D$ from the given type of reaction.
$I_2 + 2NaOH \longrightarrow NaI + NaOI + H_2O$

When white phosphorus reacts with caustic soda $(NaOH)$,$PH_3$ and $NaH_2PO_2$ are formed. This reaction is an example of what?

Assign $A$,$B$,$C$,$D$ from the given type of reaction.
$H_2O_2 \xrightarrow{R.T} H_2O + \frac{1}{2} O_2$

$Cl_2 + NaOH$ (dil. and cold) $\longrightarrow A + B + H_2O$. The anions of $A$ and $B$ are respectively . . . . . .