Chemical reactions
90 past-paper questions on Chemical reactions · examined 2023–2025.
20258 questions
Some physical and chemical changes are listed. Which changes are physical changes?
Blue copper(II) sulfate crystals are heated in air until they turn into a white powder. The powder is allowed to cool and after a few days it starts to turn blue. Why does the white powder start to turn blue?
Carbon reacts with silver oxide to form carbon dioxide and silver. Which substance is reduced?
Aluminium reacts with iron(III) oxide to form aluminium oxide and iron. Which chemical equation for the reaction between aluminium and iron(III) oxide is correct?
Which statement describes the effect of adding a catalyst to a chemical reaction?
Which equations show the underlined species acting as a reducing agent?
Describe what is observed when potassium is added to water.
Complete the symbol equation for this reaction.
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