Metals low in the activity series are very unreactive. The oxides of these metals can be reduced to metals by heating alone.
2HgO(s) → 2Hg(l) + O(g)
The metals in the middle of the activity series such as iron, zinc, lead, copper, etc., are moderately reactive. These metal oxides are reduced to the corresponding metals by using suitable reducing agents
ZnO(s) + C(s) → Zn(s) + CO(g)
The metals high up in the reactivity series are very reactive. They are separated from their oxides by electrolysis process.
