Brass gets discoloured in air because of the presence of which of the following

Brass gets discoloured in air because of the presence of which of the following gases in air?

View More Related Question

1) A chronometer measures

2) Which of the following is not an isotope of hydrogen?

3) One kilometre is equal to how many miles?

4) Which of the following is a protein?

5) Which of the following is used as a lubricant?