why does the earth behave like a giant magnet? why the hole in the ozone layer is above Antarctica but not polluted continents? in a fractional distillating column of liquid air, the 'exit' of oxygen gas (b.p. -183C) is below the argon gas (b.p. -186C). However, when the liquid air encounters the 'exit' of oxygen gas which is at -183C, the argon also boils. So we cannot seperate the oxygen and argon. What's wrong with my concept?