Question

Which of the following is an example of a visual indicator?

• A. Onion
• B. Clove
• C. Extract of red cabbage
• D. Vanilla extract

Answer 1

The correct option is C

Extract of red cabbage

A visual indicator is a natural or a synthetic indicator that changes its colour on the addition of an acid or a base.
Red cabbage extract is a purplish- blue coloured solution that turns red in acidic medium and green in basic medium. So, red cabbage extract is an example of a visual indicator.

Onion, clove and vanilla extract are olfactory indicators because they respond to acids and bases by change in odour.