What this practice covers
These questions are drawn from past CIE 0620 Chemistry papers and filtered to formulae. 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 formulae, taken from our own topic notes. Read them before you practise and you will recognise the traps in the questions.
- Writing O, H or Cl instead of O₂, H₂ and Cl₂.
- Balancing by changing a subscript rather than the number in front.
- Losing the bracket in Ca(NO₃)₂ or Al₂(SO₄)₃.
- Leaving state symbols out, especially the (s) that marks a precipitate.
- Including spectator ions in an ionic equation.
- Balancing the atoms but not the charge in an ionic equation.
- Counting only the first molecule when a big number multiplies the whole formula.
Revise it first
If any of the above is unfamiliar, work through the notes before practising: Formulae revision notes.