$KMnO_4$ acts as an oxidising agent in acidic medium. $X$ is the difference between the oxidation states of $Mn$ in reactant and product. $Y$ is the number of $d$ electrons present in the brown red precipitate formed at the end of the acetate ion test with neutral ferric chloride. The value of $X+Y$ is $.........$

Explain the uses of indicators in the analysis of redox reactions.

$500$ mL of $0.2$ $M$ $MnO_4^-$ solution in basic medium when mixed with $500$ mL of $1.5$ $M$ $KI$ solution, oxidises iodide ions to liberate molecular iodine. This liberated iodine is then titrated with a standard $x$ $M$ thiosulphate solution in presence of starch. If $300$ mL of thiosulphate was consumed, then the value of $x$ is . . . . . . .

Match the reactions in Column $I$ with the nature of the reactions/type of the products in Column $II$.

Column $I$	Column $II$
$A$. $O_2^{-} \rightarrow O_2 + O_2^{2-}$	$p$. redox reaction
$B$. $CrO_4^{2-} + H^{+} \rightarrow$	$q$. one of the products has trigonal planar structure
$C$. $MnO_4^{-} + NO_2^{-} + H^{+} \rightarrow$	$r$. dimeric bridged tetrahedral metal ion
$D$. $NO_3^{-} + H_2SO_4 + Fe^{2+} \rightarrow$	$s$. disproportionation

Assign $A, B, C, D$ from the given type of reaction.
$2F_2 + 2H_2O \longrightarrow 4HF + O_2$

$KI$ is oxidised into $I_2$ by using the reagent