Thermal decomposition of a $Mn$ compound $(X)$ at $513 \ K$ results in compound $Y$,$MnO_2$ and a gaseous product. $MnO_2$ reacts with $NaCl$ and concentrated $H_2SO_4$ to give a pungent gas $Z$. Identify $X, Y$ and $Z$.

Which diagram correctly represents the change in the color of an aqueous solution of chromate ions?

$I$. $4FeCr_2O_4 + 16NaOH + 7O_2 \rightarrow 8Na_2CrO_4 + 2Fe_2O_3 + 8H_2O$ (where $A = Na_2CrO_4$)
$II$. $2Na_2CrO_4 + H_2SO_4 \rightarrow Na_2Cr_2O_7 + Na_2SO_4 + H_2O$ (where $B = H_2SO_4$)
Compounds $(A)$ and $(B)$ are :

Determine the correct $(T)$ and incorrect $(F)$ statements from the following:
$(a)$ In the titration of $C_2O_4^{2-}$ with $KMnO_4$,$C_2O_4^{2-}$ acts as an oxidizing agent.
$(b)$ $KMnO_4$ is a strong oxidizing agent.
$(c)$ In $Cr_2O_4^{2-}$,the $O-Cr-O$ bond angle is $120^o$.
$(d)$ The standard electrode potential for the reaction $Cr_2O_7^{2-} + 14H^+ + 6e^- \to 2Cr^{3+} + 7H_2O$ is $E^o = -1.33 \ V$.

The bonds present in the structure of dichromate ion are:

What is the use of potassium permanganate $(KMnO_4)$?