Showing that air contains about one-fifth oxygen
2 marks · EasyA 250 cm³ sample of dry, unpolluted air is analysed.
Calculate the approximate volume of argon in the sample. Give your answer to 2 decimal places.
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2.25 cm³ (±0.05)
Common mistakes: 0.9; 22.5; incorrect percentage used
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Marking points
M1 · 1 mark · Use correct percentage for argon (0.9%) and multiply by 250 cm³
A1 · 1 mark · Correctly calculates 2.25 cm³ (accept 2.25, unit required for full accuracy mark) (follow-through)
Worked solution
Argon makes up 0.9% of air.