Which of the following act as an oxidising as well as a reducing agent?

$KMnO_4$ 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 $.........$

Which of the following is not correctly matched?

Assign $A, B, C, D$ from the given type of reaction.
$K_2Cr_2O_7 + 2NaOH \longrightarrow 2K_2CrO_4 + H_2O$
Identify the nature of the product $CrO_4^{2-}$ formed in the reaction.

Which of the following changes does not occur when $K_2Cr_2O_7$ reacts with $H_2O_2$ solution?

$H_2O_2$ reduces $KMnO_4$ in acidic medium to '$x$' and in basic medium to '$y$'. What are $x$ and $y$?