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.

percent abundance for cu-63 can be shown as:

63 x + 65 (1-x) = 62.9296

65 - 62.9296 = 2 x

x = 1.035

thus, percent abundance for cu-63 is 1.035

percent abundance for cu-65 can be shown as:

63 x + 65 (1-x) = 64.9278

65 - 64.9278 = 2 x

x = 0.0361

thus, percent abundance for cu-63 is 0.0361

the mass spectrum of cu-63 showing the intense peak as, this isotope is found in nature more abundantly around 92.38 % in comparison to cu-65 which is found 62.58 % naturally