In the balanced chemical reaction
$IO_3^- + aI^- + bH^+ \to cH_2O + dI_2$
$a, b, c, d$ respectively correspond to

The number of electrons required to balance the following equation $NO_3^- + 4H^+ + x e^- \to 2H_2O + NO$ is

The equivalent weight of $Na_2S_4O_6$ in the reaction $2Na_2S_2O_3 + I_2 \to Na_2S_4O_6 + 2NaI$ is :-

In the given chemical reaction,colors of the $Fe^{2+}$ and $Fe^{3+}$ ions,are respectively :
$5 Fe^{2+} + MnO_{4}^{-} + 8 H^{+} \rightarrow Mn^{2+} + 4 H_{2} O + 5 Fe^{3+}$

How many moles of acidified $K_{2}Cr_{2}O_{7}$ are required to liberate $6$ moles of $I_{2}$ from an aqueous solution of $I^{-}$?

For the redox reaction $MnO_4^- + C_2O_4^{2-} + H^{+} \to Mn^{2+} + CO_2 + H_2O$,the correct coefficients of the reactants for the balanced reaction are:
$MnO_4^-$ : $C_2O_4^{2-}$ : $H^{+}$