AI-generated practice question — model-generated for extra practice, not a previous-year CBSE board question.
When litmus solution is neither acidic nor basic (i.e., neutral), its colour is purple.
Source: Introduction, Chapter 2
The textbook explicitly states: "Litmus solution is a purple dye... When the litmus solution is neither acidic nor basic, its colour is purple." Students often only remember that acids turn litmus red and bases turn it blue, forgetting the neutral (original) purple colour. This is a direct one-line fact question — just state the colour clearly.