For the redox reaction $xP_4 + yHNO_3 \to H_3PO_4 + NO_2 + H_2O$,find the values of $x$ and $y$.

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 $Mn^{2+}$?

Assign $A$,$B$,$C$,$D$ from the given type of reaction.
$Ca(OH)_2 + SO_2 \longrightarrow CaSO_3 \downarrow + H_2O$

Explain the balancing of a redox reaction by the oxidation number method.

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

Assign $A, B, C, D$ from the given type of reaction.
$NaNO_2 + FeSO_4 + H_2SO_4 \longrightarrow [Fe(H_2O)_5NO]SO_4 + Na_2SO_4 + Fe_2(SO_4)_3 + H_2O$
Identify the type of reaction for the formation of the brown ring complex.