A sheet of aluminum (Al) foil has a total area of 1.000 ft2 and a mass of 3.636 g. What is the thickness of the foil in millimeters? (Density of Al = 2.699 g/cm3.) 1.89 Comment on whether each of the following is a homogeneous mixture or a heterogeneous mixture:
(a) Air in a closed bottle
(b) Air over New York City.