$1 \text{ mole of } H_2C_2O_4 \text{ is oxidised by } x \text{ mole of } MnO_4^- \text{ in strong basic medium and } 1 \text{ mole of } NaHC_2O_4 \text{ is oxidised by } y \text{ mole of } MnO_4^- \text{ in acidic medium. Ratio of } x/y \text{ is}$

Which of the following is not a redox reaction?

To measure the quantity of $MnCl_2$ dissolved in an aqueous solution,it was completely converted to $KMnO_4$ using the reaction,
$MnCl_2 + K_2S_2O_8 + H_2O \longrightarrow KMnO_4 + H_2SO_4 + HCl$ (equation not balanced).
Few drops of concentrated $HCl$ were added to this solution and gently warmed. Further,oxalic acid $(225 \ mg)$ was added in portions till the colour of the permanganate ion disappeared. The quantity of $MnCl_2$ (in $mg$) present in the initial solution is . . . . . . . . . (Atomic weights in $g \ mol^{-1}: Mn = 55, Cl = 35.5$ )

$X(aq.) + Na_2O_2 \to Y(aq.) \xrightarrow{BaCl_2} Z \downarrow_{\text{Insoluble in dil. } HCl}$
$X$ and $Y$ are different sodium salts. Then the anion present in the salt $(X)$ is:

$A$ solution of $KMnO_{4}$ on reduction yields either a colourless solution,a brown precipitate,or a green solution depending on the $pH$ of the solution. What different stages of the reduction do these represent and how are they carried out?

What change does not occur when $K_2Cr_2O_7$ reacts with $H_2O_2$ solution in an acidic medium?