Question

which of these can be used by a visually impaired student?

a) litmus b)turmeric c)petunia leaves d)vanilla essence e)red litmus

Answer 1

Ans is Vanilla essence. It is olfactory indicator. Vanilla extract has the characteristics pleasant smell. If a basic solution is added to the vanilla extract, then we cannot detect its smell.However an acidic solution like HCl does not destroy the smell of vanilla extract.