What this practice covers
These questions are drawn from past CIE 0620 Chemistry papers and filtered to exothermic and endothermic reactions. 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 exothermic and endothermic reactions, taken from our own topic notes. Read them before you practise and you will recognise the traps in the questions.
- Saying an exothermic reaction takes in energy because the reaction "gets hot". It is the surroundings that gain the energy.
- Giving ΔH a positive value for an exothermic reaction, or leaving the sign off altogether.
- Measuring the activation energy from the products rather than from the reactants.
- Drawing an endothermic diagram with the products below the reactants.
- Saying bond breaking releases energy. It always absorbs energy.
- Subtracting the bonds broken from the bonds made, giving the right number with the wrong sign.
- Forgetting the balancing numbers when counting bonds.
Revise it first
If any of the above is unfamiliar, work through the notes before practising: Exothermic and endothermic reactions revision notes.