Extraction of a metal (M) from its sulphide ore (M₂S) involves the following chemical reactions

$$2{M_2}S + 3{O_2}\buildrel {Heat} \over \longrightarrow 2{M_2}O + 2S{O_2} \uparrow $$

$${M_2}S + 2{M_2}O\buildrel {Heat} \over \longrightarrow 6M + S{O_2} \uparrow $$

The metal (M) may be

In the Bayer's process, the leaching of alumina is done by using

A copper coin was electroplated with Zn and then heated at high temperature until there is a change in colour. What will be the resulting colour?