Imagine you're a forensic chemist. A mysterious liquid sits on your bench. No labels. You need to know — is it an acid, a base, or something neutral? Your weapon: indicators.
Step 1 — Choose Your Indicator
📊 Complete Reference Table
Indicator
In Acid
Neutral
In Alkali
Litmus
Red
Purple
Blue
Methyl Orange
Red
Orange
Yellow
Thymolphthalein
Colourless
Colourless
Blue
⚠️EXAMINER TRAP
Thymolphthalein in acid is COLOURLESS — not "clear", not "transparent". Cambridge mark schemes require the word colourless. Writing "clear" scores zero because "clear" means transparent (e.g., glass), not absence of colour.
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