I. It has a varied composition from one place to another. II. It constituents can be separated by physical means. III. It contains unreactive noble gases Wh...

The characteristics of a mixture are that it has a varied composition from one place to another and its constituents can be separated by physical means. Air meets both of these criteria, as it has a different composition depending on where it is sampled from and its components (oxygen, nitrogen, carbon dioxide, etc.) can be separated by physical means such as fractional distillation or filtration. The presence of unreactive noble gases such as helium and neon in air is not necessarily an indication that air is a mixture, as pure samples of these gases can also be obtained through other means. Therefore, the options that show that air is a mixture are I and II only.