Air is a homogeneous mixture and its components can be separated by fractional distillation.

The flow diagram shows the steps involved in the process

Air

↓

Compressed and cooled by increasing pressure and decreasing temperature.

↓

Liquid Air

↓

Allow to warm up slowly in fractional distillation column.

↓

Gases get separated at different heights.

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                     Oxygen - Argon - Nitrogen

Boiling Point(C) -183      -186        -196

% Air by volume  20.9    0.9          78.1