Which location would have the most air molecules per cubic foot?

Question

Death Valley (below sea level)

Miami (at sea level)

Denver (above sea level)

Answer 1

Death Valley.

At lower elevations the air has greater density.

Answer 2

death valley.

it is below sea level, and therefore experiences the most gravity.

at higher altitudes, the oxygen molecules are few because there is less gravity. therefore, there are less oxygen molecules per cubic foot