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Science (086) — AI-generated practice question

AI-generated practice question — model-generated for extra practice, not a previous-year CBSE board question.

Q1. [1] straightforward exam-ready
Among the following, which is an olfactory indicator? (A) Litmus (B) Phenolphthalein (C) Onion (D) Methyl orange
  1. A Litmus
  2. B Phenolphthalein
  3. C Onion
  4. D Methyl orange
Generated by claude-sonnet-4-6 · 2026-06-26 01:03 · grounding rag
Model Answer

(C) Onion

Onion is an olfactory indicator because its odour changes in acidic or basic media, unlike litmus, phenolphthalein, and methyl orange, which are colour-change indicators.

Explanation

Olfactory indicators are substances whose smell (not colour) changes in acidic or basic solutions. The textbook (Activity 2.2) uses onion, vanilla, and clove oil as examples. Litmus, methyl orange, and phenolphthalein are visual (colour-change) indicators. Examiners expect you to know the definition and one example.

Previous-year CBSE Grade 10 board exam questions, organised by subject and chapter, each with a model answer — free to read and print.