Atoms and molecules
3 marks · NormalMethane (CH₄) is a molecule made from one carbon atom and four hydrogen atoms. Calculate the total number of atoms in five molecules of methane. Show your working.
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25 atoms (±0)
Must show: working out atoms per molecule, multiplying by number of molecules
Common mistakes: Counting only atoms of one type; Incorrect multiplication
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Marking points
M1 · 1 mark · Identifies total atoms in one methane molecule as 5 (1 carbon + 4 hydrogen).
M1 · 1 mark · Multiplies correctly by 5 molecules. (follow-through)
A1 · 1 mark · Gives correct final answer: 25 atoms. (follow-through)
Worked solution
Each methane (CH₄) molecule has 1 carbon atom + 4 hydrogen atoms = 5 atoms.
Final answer: 25 atoms.