Showing that air contains about one-fifth oxygen
2 marks · HardArgon and carbon dioxide are both present in dry, unpolluted air. Which is present in a larger amount? Give an approximate percentage for both gases.
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Argon is present in a larger amount than carbon dioxide. Approximate percentages: argon = 0.9%, carbon dioxide = 0.04%.
Also accept: Argon, about 0.9%; carbon dioxide, about 0.04%; Argon (0.9%), carbon dioxide (0.04%); Argon (greater), 0.9%; CO2 0.04%
Common mistakes: Reversing percentages; Stating carbon dioxide is more abundant
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Marking points
B1 · 1 mark · Identifies argon is present in a larger amount than carbon dioxide.
B2 · 1 mark · Gives approximate percentages: argon = 0.9%, carbon dioxide = 0.04%.
Worked solution
Argon is present in a larger amount than carbon dioxide in dry, unpolluted air.
Approximate percentages: argon = 0.9%, carbon dioxide = 0.04%.