Aqueous solutions of hydrogen sulphide and sulphur dioxide when mixed together,yield

Assign $A$,$B$,$C$,$D$ from the given type of reaction.
$I_2 + S_2O_3^{2-} \longrightarrow I^{-} + S_4O_6^{2-}$

Assign $A, B, C, D$ from the given type of reaction.
$2NaNO_3 \xrightarrow{\Delta} 2NaNO_2 + O_2$

In the chemical reaction between stoichiometric quantities of $KMnO_4$ and $KI$ in a weakly basic or neutral solution,what is the number of moles of $I_2$ released for $4$ moles of $KMnO_4$ consumed?

Write the balanced chemical equations for the following reactions:
$(1)$ Reaction between $MnO_4^-$ and $I^-$ in neutral or faintly alkaline solution.
$(2)$ Reaction between $MnO_4^-$ and $C_2O_4^{2-}$ in acidic medium $(H^+)$.

Assign $A, B, C, D$ from the given type of reaction for the following chemical equation:
$3Fe_{(s)} + 4H_2O_{(g)} \xrightarrow{\Delta} Fe_3O_{4(s)} + 4H_{2(g)}$