A metal 'P' when exposed to moist air for longer period of times, loses its shining brown surface and gains green coating, what has happened ? Identify the metal, write the name and chemical formula of green coloured compound. List two ways to prevent this process.

Explanation

The metal is copper. It is shining brown in colour. In the presence of moist air, surface of the metal acquires a green coating due to the formation of basic copper carbonate which is `Cu(OH)_(2).CuCO_(3)`.
`2Cu+underset("Present in air")ubrace(H_(2)O+CO_(2)+O_(2)) rarr underset(("Green"))underset("Basic copper carbonate")(Cu(OH)_(2)CuCO_(3))`
The process known as corrosion can be prevented by either painting the surface of the metal or applying a coating of grease from time to time so that the water drops may not stick to the surface.