Which of the following statements is incorrect?

Oxidation states of the metal in the minerals haematite and magnetite,respectively,are

Identify the reactions in which dichromate acts as an oxidising reagent.
$I$. $Cr_2O_7^{2-} + 6Fe^{2+} + 14H^{+} \longrightarrow 2Cr^{3+} + 6Fe^{3+} + 7H_2O$
$II$. $Cr_2O_7^{2-} + 2OH^{-} \longrightarrow 2CrO_4^{2-} + H_2O$
$III$. $Cr_2O_7^{2-} + 6I^{-} + 14H^{+} \longrightarrow 2Cr^{3+} + 3I_2 + 7H_2O$
$IV$. $Na_2Cr_2O_7 + 2KCl \longrightarrow K_2Cr_2O_7 + 2NaCl$

On heating $KMnO_4$,one among the following is not formed:

$X + H^{+} \rightarrow Y + Na^{+} + H_2O$
$Y + KCl \rightarrow K_2Cr_2O_7 + NaCl$
Identify $X$ and $Y$ in the given reactions.

When a mixture of manganese dioxide,potassium hydroxide and potassium chlorate is fused,the product obtained is