$Na_2S_2O_3 + I_2 \to$ Product is

$KMnO_4$ oxidises oxalic acid in acidic medium. The number of $CO_2$ molecules produced per mole of $KMnO_4$ is

For the redox reaction
$MnO_{4}^{-} + C_{2}O_{4}^{2-} + H^{+} \longrightarrow Mn^{2+} + CO_{2} + H_{2}O$
the correct coefficients of the reactants for the balanced equation are
$MnO_{4}^{-} \quad C_{2}O_{4}^{2-} \quad H^{+}$

In the balanced chemical equation $MnO_4^- + Br^- + H_2O \to MnO_2 + BrO_3^- + OH^-$,the coefficients of $MnO_4^-$,$BrO_3^-$,and $OH^-$ are respectively:

What is the value of $x$ in order to balance the following redox reaction?
$Mn_{(aq)}^{2+} + x ClO_{3_{(aq)}}^{-} \rightarrow MnO_{2_{(s)}} + x ClO_{2_{(aq)}}$

How many electrons are needed to reduce $N_2$ to $NH_3$?