Give the steps involved in the extraction of metals of low and medium reactivity from their respective sulphide ores. 

Explanation

Extraction of Mercury : Mercury is a metal of low reactivity. Cinnabar, i.e., mercury (II) sulphide is the ore of mercury. It is heated in air so that it is oxidized to produce mercury (II) oxide. After that, mercury oxide is reduced to obtain mercury.
The following reactions are involved in this process.
`2HgS + 3O_(2) rarr 2HgO + 2SO_(2)`
Extraction of metals of medium reactivity series : The metals in the middle of the reactivity series are also extracted by roasting, followed by reduction but the methods are somewhat different.
Extraction of Zinc : Zinc is in the middle of the reactivity series. It is found in the form of zinc blend which is zinc oxide. It is first heated in the presence of air to obtain zinc oxide. This process can be shown by following equation.
`2ZnS + 3O_(2) rarr 2ZnO + 2SO_(2)`
After that, zinc oxide is reduced to obtain pure zinc metal. The reduction is done in the presence of carbon. This can be shown by following equation.
`ZnO + C rarr Zn + CO`