What are olfactory indicators? Give one example from the chapter.
Generated by claude-sonnet-4-6 · 2026-06-17 12:32 · grounding rag
Model Answer
Olfactory indicators are substances whose smell (odour) changes in acidic or basic conditions. They are used to detect the presence of acids or bases.
Example: Onion and clove oil are olfactory indicators. The smell of onion disappears in a basic solution, while it remains in an acidic solution.
Source: Chapter 2, Acids, Bases and Salts
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Explanation
- The term "olfactory" relates to smell (olfactory receptors detect smell, as mentioned in Chapter 6).
- CBSE expects students to define the term clearly and give at least one valid example. Onion and clove oil are the standard textbook examples for olfactory indicators.
- Do not confuse with litmus or turmeric (those are colour-change indicators, not smell-based).
- For 2 marks: 1 mark for correct definition + 1 mark for correct example.