Which of the following is incorrect about $K_{2}Cr_{2}O_{7}$?

$A$ compound of mercury used in cosmetics,in Ayurvedic and Yunani medicines and known as vermilion is

$Orange-(A)$ (Inorganic compound) $+ H^{+} + H_2O_2 \to Blue-(B)$. The oxidation state of the central atom in compound $(B)$ is:

Which one of the following ions participates in the production of $ATP$ from the oxidation of glucose?

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

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