Question

Paragraph on olfactory indicators

Answer 1

The term olfactory means relating to sense of smell. Those substances whose smell changes in acidic or basic solution are called as olfactory indicators. It works on the principle that when an acid or base is added to it, its characteristic smell cannot be detected. Onion and vanilla extract are olfactory indicators.

2. Eg. : 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, does not destroy the smell of onions. This is used as a test for acids and bases.