What is the ratio of the stoichiometric coefficient of $N_2H_4$ to $Cl^-$ in the following balanced redox reaction?
$ClO_3^- + N_2H_4 \to NO_3^- + Cl^-$

For the balanced redox reaction $aZn + b \, HNO_3 \to c \, Zn(NO_3)_2 + d \, NH_4NO_3 + 3H_2O$,the value of $b$ is:

Assign $A, B, C, D$ from the given type of reaction.
$CuSO_4 + 2KCN \longrightarrow CuCN \downarrow + (CN)_2 \uparrow + K_2SO_4$

In the redox reaction
$x \ MnO + y \ PbO_2 + z \ HNO_3 \to a \ HMnO_4 + b \ Pb(NO_3)_2 + c \ H_2O$
Find the values of $x, y, z$.

In the redox reaction $xMnO + yPbO_2 + zHNO_3 \to HMnO_4 + Pb(NO_3)_2 + H_2O$,determine the values of $x, y,$ and $z$.

Manganese ions $(Mn^{2+})$ can be oxidised by persulphate ions $(S_2O_8^{2-})$ according to the following half-equations:
$S_2O_8^{2-} + 2e^- \longrightarrow 2SO_4^{2-}$
$Mn^{2+} + 4H_2O \longrightarrow MnO_4^- + 8H^+ + 5e^-$
How many moles of $S_2O_8^{2-}$ are required to oxidise $1 \ mole$ of $Mn^{2+}$?