What this practice covers
These questions are drawn from past CIE 9701 Chemistry papers and filtered to hydrocarbons. You answer, you find out immediately whether you were right, and you get the reasoning for the correct option and for each distractor. Wrong answers go to a mistakes locker so you can come back to exactly those.
Practice is free. You need an account only so your progress and your mistakes are still there next time.
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What examiners see students get wrong here
These are the errors that cost marks on hydrocarbons, taken from our own topic notes. Read them before you practise and you will recognise the traps in the questions.
- Saying benzene decolourises bromine water. It does not react with bromine without a halogen carrier.
- Explaining substitution over addition by saying the ring is "very stable" without saying that addition would destroy the delocalised system and lose the stabilisation.
- Giving NO₂ rather than NO₂⁺ as the electrophile in nitration, or omitting the equation that generates it.
- Drawing the intermediate as a complete ring, or without the positive charge.
- Drawing the final curly arrow from the ring to the hydrogen rather than from the C-H bond into the ring.
- Leaving out the step that regenerates the catalyst.
- Giving the nitration temperature as "warm" or above 60 °C, where dinitration occurs.
- Predicting side-chain substitution under a halogen carrier, or ring substitution under ultraviolet light.
Revise it first
If any of the above is unfamiliar, work through the notes before practising: Hydrocarbons revision notes.