Practise O/L exam questions on Chemical Reactions and Equations with worked solutions
2022 · Paper II · 5 marks
Magnesium ribbon burns in oxygen to form magnesium oxide.
(i) Write the balanced chemical equation for this reaction.
(ii) Classify this as a combination, decomposition, displacement or double-displacement reaction.
(iii) Name TWO signs that indicate a chemical reaction has occurred in this experiment.
Show worked solution
(i) 2Mg + O₂ → 2MgO
(ii) Combination (synthesis) reaction — two substances combine to form one product.
(iii) Bright white light / flame produced; white ash (MgO) forms (any two of: light, heat, new substance formed, colour change accepted).