Question

The oxides of which of the following ores can be reduced by just heating?

• A. Haematite
• B. Magnetite
• C. Cinnabar
• D. Calamine

Answer 1

The correct option is C Cinnabar

Haematite $\left(F{e}_2{O}_3\right)$
Magnetite $\left(F{e}_3{O}_4\right)$
Cinnabar $\left(HgS\right)$
Calamine $\left(ZnC{O}_3\right)$

Reduction of oxides of less reactive metals can be done by just heating. Hg is the least active metal of all. So its ore, HgS, can be reduced just by heating.
On the other hand, Fe and Zn are moderately reactive metals.