What this practice covers
These questions are drawn from past CIE 0620 Chemistry papers and filtered to alkenes. 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.
Start practising practice questions →
What examiners see students get wrong here
These are the errors that cost marks on alkenes, taken from our own topic notes. Read them before you practise and you will recognise the traps in the questions.
- Writing the bromine water result as "clear" or "white" instead of colourless.
- Saying the alkane also decolourises bromine water, just more slowly. It does not react at all.
- Writing an addition product with a by-product, such as CH₂=CH₂ + Br₂ → CH₂BrCH₂Br + HBr. Addition has one product only.
- Putting both bromines on the same carbon.
- Giving a cracking equation that does not balance, or one whose products are all saturated.
- Confusing the two catalysts: nickel is for hydrogen, phosphoric acid is for steam.
- Saying cracking needs a high pressure. The stated conditions are high temperature and a catalyst.
Revise it first
If any of the above is unfamiliar, work through the notes before practising: Alkenes revision notes.