On a weight basis, air contains the following proportion of oxygen_________________?
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Answer: B. 23
Explanation
Chemical composition of dry atmospheric air on a mass basis consists of approximately twenty-three percent oxygen. Nitrogen makes up the remaining seventy-seven percent of dry air mass, alongside trace noble gases. Standard engineering calculations rely on these weight proportions when analyzing combustion air requirements. Molar mass of oxygen is thirty-two grams per mole, while nitrogen has a molar mass of twenty-eight. Volumetric proportions differ from mass proportions, with oxygen comprising roughly twenty-one percent by volume. Dry air composition remains remarkably constant across the lower layers of the Earth atmosphere.
Combustion stoichiometry calculations for boilers and internal combustion engines require accurate air mass ratios. Environmental engineering studies use air composition data to model atmospheric pollution dispersion. Aerospace engineering incorporates air density and mass fractions for aerodynamic performance calculations. Twenty-one percent represents the volumetric percentage of oxygen in dry air rather than its mass proportion. Twenty-five percent overestimates the actual oxygen mass content found in natural atmospheric air. Seventy-three percent corresponds roughly to incorrect mass fractions that do not match standard air tables.
- Subject
- Engineering
- Category
- Mechanical Engineering
- Topic
- —
- Difficulty
- medium
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