Q. Which of the following is/are correct for olfactory indicators?

1. Their colour changes with acid or base.
2. Onion, vanilla or clove are examples.

Select the correct answer from the codes given below:
Answer: Only 2
Notes: There are some substances whose odour changes in acidic or basic media. These are called olfactory indicators. Olfactory indicators can be used in the laboratory to test whether a solution is a base or an acid, a process called olfactory titration. Onion, clove oil and vanilla extract are examples of olfactory indicators.

This question is part of UPSC Daily 20 MCQ Series Course on GKToday Android app.