Question

what are olfactory indicators

Answer 1

What Are Olfactory Indicators? 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 a base or an acid, a process called olfactory titration

Answer 2

Those substances whose smell (or odour) changes in acidic or basic solution are called olfactory indicators onion and vanilla extract are olfactory indicators.