Contents
Part 1 of 3
Acid, alkali or neutral?
identify
Try it yourself
Limewater is a solution of calcium hydroxide, an alkali. A drop of limewater is added to each of three indicators. Which row gives the colours correctly?
identify: name or select.
| Row | Litmus | Methyl orange | Thymolphthalein |
|---|---|---|---|
| A | red | yellow | blue |
| B | blue | red | blue |
| C | blue | yellow | colourless |
| D | blue | yellow | blue |
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Scope and sources
Cambridge IGCSE Chemistry 0620 · 2026–2028 v2 · Original learning materials.
The characteristic properties of acids and bases (7.1 Core 1 to 8; Supplement 9 to 12): indicator colours, acids and bases with metals, bases, carbonates and ammonium salts, H⁺ and OH⁻ ions, the pH scale and universal indicator, neutralisation, proton donors and acceptors, and strong and weak acids. Acidic, basic and amphoteric oxides are in the module Oxides, preparing salts in Making salts and titration in Titration.
Apparatus, amounts and times in the experiment are illustrative. Real practical work follows a teacher-approved safety method.
Official Cambridge syllabus