Treatment of alkaline $KMnO_{4}$ solution with $KI$ solution oxidises iodide to:

In acidic medium,potassium dichromate acts as an oxidant according to the equation,$Cr_2O_7^{2-} + 14H^{+} + 6e^- \to 2Cr^{3+} + 7H_2O$. What is the equivalent weight of $K_2Cr_2O_7$? (Molecular weight $= M$)

In the balanced reaction $x\,MnO_4^- + y\,H_2O \to 2Mn^{2+} + 5H_2O + 9O_2 + z\,e^-$,what are the values of $x$,$y$,and $z$?

$PbS + 4O_3 \,\to ?\,+\,4O_2$

$KMnO_4$ oxidises oxalic acid to $CO_2$ in acidic medium. The equivalent weight of $KMnO_4$ is $(Mn = 55, K = 39, O = 16)$:

Assign $A$,$B$,$C$,$D$ from the given type of reaction.
$H_3PO_2 + CuSO_4 + H_2O \longrightarrow Cu + H_3PO_4 + H_2SO_4$