Question

When acid and bases added to onion and vanilla (olfactory) each. what changes happen to their odour?

Answer 1

Then after added the olfactory indicater like vanilla or onion in base or acid then it cannot detected it smell.
onion and vanilla extract are olfactory indicator.
I hope it helps your

Answer 2

An olfactory indicator works on the principle that when an acid or base is added to it,then different odour can be detected in bases whereas odour remains same in acids.Certain substances changes odour in acidic or basic medium.
1.Onion:- Paste or juice of onion loses its smell when added with base.It does not change its smell with acid.
2.Vanilla:- The smell of vanilla vanishes with base,but it’s smell does not vanishes with an acid.