Why is air called a homogeneous mixture?

Air is called a homogeneous mixture because all of the elements that make up air (oxygen, nitrogen, argon, carbon dioxide etc.) are not able to be distinguished between when you look at air.

Explanation:

A heterogeneous mixture would be something like trail mix. You can look at the bowl of trail mix and pick out the raisins from the nuts from the chocolate. A homogeneous mixture is something where the individual elements can't be picked out by the plain eye. When you look at air you can't say oh that part is oxygen and that is argon when you are going on a walk. Air is a solution and thus you can't pick out each part.

let that person have a turn to speak : )