Answer the following questions briefly:
 
A metal 'X', on long exposure to moist air containing carbon dioxide, forms a green layer 'Y'.
i. Identify 'X' and 'Y'.
ii. Write the balanced chemical equation.
iii. Name of the green layer formed.
 
i. 'X' is and 'Y' is .
ii. Which substances in the air cause corrosion of copper?.
iii. The green layer is called as.