I need help on my science question?

Question

How do you seperate the elements in the air and what parts cannot be seperated ?

Answer 1

One compresses and chills air until it liquefies. Then, in the manner of Air Products & Chemicals of Pennsylvania, one distils liquid air. One sets up a fractionation column in which higher-boiling liquids oxygen continually descends the column, while higher boiling nitrogen rises to the top. The nitrogen is separated from the oxygen. Argon and other rare gases are separated also.

Please pardon me: There are no components of air that cannot be separated. There are companies that separate every molecule.