Atoms and molecules
2 marks · EasyEach molecule of carbon dioxide (CO₂) contains one carbon atom and two oxygen atoms. How many atoms are present in four molecules of carbon dioxide? Show your working.
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12 (±0)
Common mistakes: Multiplying by incorrect numbers (e.g., 2 × 4 = 8 instead of (1+2) × 4 = 12); Only counting oxygen atoms
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Marking points
M1 · 1 mark · Correctly sums atoms in 1 molecule: 1 (C) + 2 (O) = 3.
A1 · 1 mark · Correctly multiplies by 4 to get 12 atoms.
Worked solution
Each CO₂ molecule has 1 carbon + 2 oxygen = 3 atoms. Total atoms in 4 molecules = 3 × 4 = 12.