What this practice covers
These questions are drawn from past CIE 0620 Chemistry papers and filtered to identification of ions and gases. 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 identification of ions and gases, taken from our own topic notes. Read them before you practise and you will recognise the traps in the questions.
- Reporting only what a few drops of sodium hydroxide do, without adding excess.
- Saying calcium gives a white precipitate that dissolves in excess. It does not.
- Missing the dark blue solution that copper(II) gives with excess ammonia.
- Using hydrochloric acid to acidify before adding silver nitrate.
- Using sulfuric acid to acidify before adding barium nitrate.
- Giving "white" for the silver bromide precipitate, which is cream.
- Using dry litmus paper for ammonia or chlorine.
- Swapping the two splints, or saying the limewater turns white rather than milky.
Revise it first
If any of the above is unfamiliar, work through the notes before practising: Identification of ions and gases revision notes.