Unsaturated hydrocarbons

2 marks · Easy

An alkene contains 5 carbon atoms per molecule. Calculate the number of hydrogen atoms in a molecule of this alkene.

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10 (±0)

Also accept: 10 hydrogen atoms

Common mistakes: Using alkane formula to get 12

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Marking points

M1 · 1 mark · Uses the general formula for alkenes correctly: CnH2n.

A1 · 1 mark · Writes correct final answer: 10.

Worked solution

The general formula for alkenes is . For n = 5:

So, there are 10 hydrogen atoms in the molecule.