Question

when copper articles exposed to air for a long time gets corroded.give scientific reason​

Answer 1

Answer:

Copper metal when exposed to air turns green in colour due to corrosion. When copper vessel is exposed to air in rainy season, the metal reacts with gases and moisture and atmospheric gases to form a mixture of copper carbonate and copper hydroxide. This gives a green colour to the surface of copper metal

Answer 2

Answer:

Copper metal when exposed to air turns green in colour due to corrosion. When copper vessel is exposed to air in rainy season, the metal reacts with gases, moisture and atmospheric gases to form a mixture of copper carbonate and copper hydroxide. This gives a green colour to the surface of copper metal.  

The reaction is as follows:

2Cu+H2O+CO2+O2→Cu(OH)2+CuCO3

Hence, copper becomes green when exposed to moist air for a long period of time due to the formation of a layer of basic carbonate of copper on the surface of copper.

Hope it helps you:)