AI-generated practice question — model-generated for extra practice, not a previous-year CBSE board question.
In a neutral solution, litmus appears purple in colour. Litmus is extracted from lichens, which belong to the plant division Thallophyta.
Source: Chapter 2, Introduction
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The passage explicitly states: "Litmus solution is a purple dye, which is extracted from lichen, a plant belonging to the division Thallophyta… When the litmus solution is neither acidic nor basic, its colour is purple." Examiners expect both facts — purple colour AND lichen/Thallophyta — for full credit.