What this practice covers
These questions are drawn from past CIE 0620 Chemistry papers and filtered to fertilisers. 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 fertilisers, taken from our own topic notes. Read them before you practise and you will recognise the traps in the questions.
- Saying plants take nitrogen from the air. Almost none can; the nitrogen must arrive as NH₄⁺ or NO₃⁻ in solution.
- Swapping the jobs of phosphorus and potassium. Phosphorus is for roots, potassium is for flowers, fruit and disease resistance.
- Writing ammonium as NH₃⁺ or NH₄. The ion is NH₄⁺.
- Saying the fertiliser itself poisons the fish, instead of tracing the algae, light, bacteria and oxygen chain.
- Naming the base in fertiliser manufacture as a hydroxide when the salt is an ammonium salt. The base is ammonia.
- Counting only one nitrogen atom in NH₄NO₃. There are two, one in each half of the formula.
Revise it first
If any of the above is unfamiliar, work through the notes before practising: Fertilisers revision notes.