During the extraction of $\mathrm{Ag}$ and $\mathrm{Au}$ using a $\mathrm{KCN}$ solution, cyanide ions react with metal ions as

$\mathrm{x}, \mathrm{y}$ and $\mathrm{z}$ in the following processes are respectively

(i) ${\mathrm{P}}_2{\mathrm{O}}_5+....\mathrm{x}....\to {\mathrm{Ca}}_3{\left({\mathrm{PO}}_4\right)}_2$

(ii) $2{\mathrm{Cu}}_2\mathrm{O}+{\mathrm{Cu}}_2\mathrm{S}\to .....\mathrm{y}.....+{\mathrm{SO}}_2\uparrow$

(iii) ${\mathrm{Fe}}_2{\mathrm{O}}_3+3\mathrm{CO}\to ......\mathrm{z}....+3{\mathrm{CO}}_2\uparrow$