Chemistry - Metallurgy Question with Solution | TestHub

The conversion $\mathrm{ZnS}\to \mathrm{ZnO}$ is roasting, not calcination. Calcination involves heating a carbonate or hydroxide ore in the absence of air, while roasting involves heating a sulfide ore in the presence of air to convert it to its oxide.

A. $\mathrm{CaC}{\mathrm{O}}_3\to \mathrm{CaO}$ (calcination) - Correct.

B. $\mathrm{ZnS}\to \mathrm{ZnO}$ (calcination) - Incorrect. This is roasting.

C. $\mathrm{C}{\mathrm{u}}_2\mathrm{S}\to \mathrm{Cu}$ (self-reduction) - Correct.

D. $\mathrm{Na}[\mathrm{Ag}(\mathrm{CN}{)}_2]\to \mathrm{Ag}$ (metal displacement) - Correct.