$A$ metal $X$ acquires a green colour coating on its surface on exposure to air.
$(i)$ Identify the metal $X$ and name the process responsible for this change.
$(ii)$ Name and write the chemical formula of the green coating formed on the metal.
$(iii)$ List two important methods to prevent this process.

(N/A) $(i)$ The metal $X$ is Copper $(Cu)$. The process responsible for this change is known as corrosion.
$(ii)$ The green coating is Basic Copper Carbonate. Its chemical formula is $CuCO_{3} \cdot Cu(OH)_{2}$.
$(iii)$ Two important methods to prevent corrosion are:
$1$. Painting or oiling/greasing the surface.
$2$. Galvanisation or alloying.