Question

What do you mean by olfactory indicators?

Answer 1

An olfactory indicator is a substance whose smell varies depending on whether it is mixed with an acidic or basic solution.
Olfactory indicators can be used in the laboratory to test whether a solution is acid or base, a process called olfactory titration.
onion, clove oil and vanilla extracts are examples.
That is olfactory indicators change ordour with pH