Question

coppor articles get a green layer if kept at open place for long time name the compound formed​

Answer 1

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

due to copper carbonates