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state / define / deduce
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(a) Write the formulae of carbon dioxide, ammonia and calcium carbonate. (b) A model of a molecule has one sulfur atom joined to three oxygen atoms. Write its formula, and state what this molecular formula tells you. (c) Supplement: write the empirical formula of glucose, C6H12O6. (d) Supplement: write the formula of magnesium nitrate, made of Mg2+ and NO3− ions.
state: give a concise answer. define: give the precise meaning. deduce: reach a conclusion from the information given.
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Scope and sources
Cambridge IGCSE Chemistry 0620 · 2026–2028 v2 · Original learning materials.
Formulae and equations (3.1 Core 1–4, Supplement 5–8): the formulae of the elements and compounds named in the subject content, the molecular formula, a formula from a model or diagram, word and symbol equations with state symbols and, in the Supplement, the empirical formula, ionic formulae from a model or from the charges, ionic equations and symbol equations from given information. Ions and their charges are in Ions and ionic bonding, masses and moles in later modules of topic 3, and the reactions themselves in later modules.
Apparatus, amounts and times in the experiment are illustrative. Real practical work follows a teacher-approved safety method.
Official Cambridge syllabus