some gases in air..

Write some uses of air.

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

" Write the names of the main gases in the air,"

Name the following: Two gases present in air.

Statements: Some gases are liquids. All liquids are water. Conclusions: I. All gases being water is a posability. II. All such gases which are not water can never be liquid.