The fusion of chromite ore with sodium carbonate in the presence of air leads to the formation of products $A$ and $B$ along with the evolution of $CO_2$. The sum of spin-only magnetic moment values of $A$ and $B$ is .......... $B.M.$ (Nearest integer)
(Given atomic number: $C: 6, Na: 11, O: 8, Fe: 26, Cr: 24$)

In the dichromate dianion $(Cr_2O_7^{2-})$,which of the following statements is correct regarding the $Cr-O$ bonds?

In the scheme given below,$X$ and $Y$,respectively,are:
$\text{Metal halide} \xrightarrow{\text{aq. NaOH}} \text{White precipitate } (P) + \text{Filtrate } (Q)$
$P \xrightarrow[\text{heat}]{\text{aq. } H_2SO_4, PbO_2 (\text{excess})} X (\text{a coloured species in solution})$
$Q$ $\xrightarrow[\text{warm}]{\text{MnO(OH)}_2, \text{Conc. } H_2SO_4} Y (\text{gives blue-coloration with KI-starch paper})$

$2KMnO_4 \xrightarrow{200^{\circ}C} K_2MnO_4 + MnO_2 + O_2$. Here,'$X$' is $K_2MnO_4$. Which of the following statements is correct for '$X$'?

The solution of $MnO_4^-$ is purple-coloured due to:

$X + KOH + O_2 \to Y + H_2O$,
$Y + H_2SO_4 \to Z + K_2SO_4 + MnO_2 + H_2O$
Identify $X, Y$ and $Z$ in the above reactions.