What this practice covers
These questions are drawn from past CIE 9701 Chemistry papers and filtered to group 17. 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 group 17, taken from our own topic notes. Read them before you practise and you will recognise the traps in the questions.
- Saying the covalent bonds break when iodine sublimes. Only van der Waals forces between molecules are overcome.
- Saying oxidising power increases down the group. It decreases; reducing power of the halide ions increases.
- Skipping the ammonia step in the silver nitrate test, when the precipitate colours are hard to distinguish.
- Forgetting to acidify with nitric acid before adding silver nitrate.
- Mixing up the two sodium hydroxide reactions. Cold and dilute gives chlorate(I); hot and concentrated gives chlorate(V).
- Saying chlorine itself kills the bacteria in water treatment. The active species is HClO.
Revise it first
If any of the above is unfamiliar, work through the notes before practising: Group 17 revision notes.