- Put some finely chopped onions in a plastic bag along with some clean cloth Tie up the bag tightly and keep it overnight in the fridge. The cloth strips can now be used to test for acid or base.
- Check the odour of the cloth strips.
- Keep two strips on a clean surface and put a few drops of dilute HCI on one strip and a few drops of dilute NaOH on the other
- Rinse both the strips separately with distilled water and again check their odour and note the observation.
- Take some clove oil and vanilla essence.
- Take some dilute HCl in one test tube and dilute NaOH im another test tube. Add a drop of dilute vanilla essence to both test tubes and stir well with glass rod. Check the odour and record your observations
- Test the change of odour with clove oil using dilute HCl and dilute NaOH and record your observations.
Suggest which of these- onion, vanilla essence and clove oil, can be used as olfactory indicators on the basis of your observations
