The yellow colour of chromates changes to orange on acidification due to the formation of:

$Fe_2Cr_2O_4 + Na_2CO_3 + O_2$ $\xrightarrow{\text{Fusion}} [X]$ $\xrightarrow[H_2O]{H^{+}} [Y]$ $\xrightarrow{H_2O_2/H^{+}} [Z]$
Which of the following statements is true for the compounds $[X]$,$[Y]$,and $[Z]$?

The bonds present in the structure of dichromate ion are:

Corundum is

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

Consider the following reactions:
$K_2Cr_2O_7 + NaCl + H_2SO_4 \rightarrow CrO_2Cl_2 + \text{Side Products}$
$CrO_2Cl_{2(Vapour)} + NaOH \rightarrow B + NaCl + H_2O$
$B + H^+ \rightarrow C + H_2O$
The number of terminal $'O'$ atoms present in the compound $'C'$ is $..........$