Question

_______ is olfactory indicator.

• A. Onion extract
• B. Tomato juice
• C. Tea
• D. Vinegar oil

Answer 1

The correct option is A

Onion extract

The explanation for the correct option (A):

• The term 'olfactory' refers to a person's ability to smell.
• Olfactory indicators refer to those indicators whose smell or odour changes in acidic and basic solutions.
• Examples include Vanilla and onion extract.
• Onions have a distinct aroma. When a basic solution, such as Sodium hydroxide (NaOH) solution is put to a cotton strip that has been treated with onion extract, the scent of the onion is lost. The fragrance of onions is not destroyed by an acidic solution such as Hydrochloric acid (HCl). This may be used to determine the presence of acids and bases.

Final Answer: Hence, option (A) is correct. Onion extract is an olfactory indicator.