Oxidation of thiosulphate $S_2O_3^{2-}$ ion by iodine gives

In an experiment,$50 \ mL$ of $0.1 \ M$ solution of a metal salt reacted with $25 \ mL$ of $0.1 \ M$ solution of sodium sulphite. The half-equation for the oxidation of sulphite ion is $SO_3^{2-}{(aq)} + H_2O_{(l)} \to SO_4^{2-}{(aq)} + 2H^{+}{(aq)} + 2e^-$. If the oxidation number of the metal in the salt was $3$,what would be the new oxidation number of the metal?

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

If the number of moles of $Fe^{2+}$ ions oxidized by one mole of acidified $MnO_4^{-}$ is $x$, the number of moles of $Fe^{2+}$ ions oxidized by one mole of acidified $Cr_2O_7^{2-}$ is:

For the balanced equation $NO_3^- + 4H^+ + ne^- \to 2H_2O + NO$,the value of $n$ is ........

Assign $A, B, C, D$ from the given type of reaction.
$MnSO_4 + Sr(NO_3)_2 \longrightarrow SrSO_4 \downarrow + Mn(NO_3)_2$