Question

Which of the following is NOT correct about olfactory indicators?

Statement 1: When an acid or base is added to it, then its 'characteristic smell' can not be detected.

Statement 2: Onion and Vanilla are olfactory indicators.

1. Statement 1 is correct
2. Statement 2 is correct
3. Both are correct
4. None is correct

Answer 1

Correct Answer - Option 3 : Both are correct

The correct answer is 3 i.e. Both are correct.

Explanation:

• The term 'olfactory' means 'relating to the sense of smell'.
• Those substances whose smell changes in acidic or basic solutions are called olfactory indicators. 
• An olfactory indicators usually works on the principle that When an acid or base is added to it, then its 'characteristic smell' can not be detected.
• Onion and Vanilla are olfactory indicators.
• Onion has a characteristic smell.
  • When a basic solution like sodium hydroxide solution is added to a cloth strip treated with onions, then the onion smell cannot be detected. 
  • An acidic solution like hydrochloric acid, however, does not destroy the smell of onions. This can be as a test for acidic and bases.
• Vanilla extract has a characteristic pleasant smell.
  • If a basic solution like sodium hydroxide solution is added to vanilla extract, then we can not detect the characteristics smell of vanilla extract.
  • An acidic solution like hydrochloric acid, however, does not destroy the smell of vanilla extract. This can be used as a test for acids and bases.