Atoms and molecules
2 marks · EasyA molecule of methane (CH₄) contains one carbon atom and four hydrogen atoms. Calculate the total number of atoms present in three molecules of methane. Show your working.
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15 (±0)
Common mistakes: Multiplying incorrectly (using 3*4 instead of 3*5); Adding instead of multiplying
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Marking points
M1 · 1 mark · Method: Identifies number of atoms in one molecule: 1 (C) + 4 (H) = 5 atoms, and attempts to multiply by 3.
A1 · 1 mark · Accurate answer: 15 atoms.
Worked solution
Each CH₄ molecule contains 1 carbon + 4 hydrogen = 5 atoms. Total atoms in 3 molecules = 3 × 5 = 15.