Hich of these statements explains the relationship among elements, compounds, and mixtures?

elements are made of compounds and mixtures.

both compounds and mixtures are made up of elements.

mixtures are made of elements, and elements are made of compounds.

compounds are made of mixtures, and mixtures are made of elements.

Assume that a person skiing high in the mountains at an altitude of h = 15100 ft takes in the same volume of air with each breath as she does while walking at sea level. determine the ratio of the mass of oxygen inhaled for each breath at this high altitude compared to that at sea level. assume that the air composition (i.e. % of air that is oxygen) is the same at sea level as it is at 15100 ft.