In each trial, you will add an indicator to the mystery food sample. But you will also add the

indicator to a known substance and water. Why is

that important? Check all reasons.

The correct answer is -

- to match the mystery food sample to a definite positive result (gelatin, oil.)

- to match the mystery food sample to a definite negative result (water)

Explanation:

Adding an indicator or any indicator to an unknown food sample or any sample and then adding the same indicator to the known sample is necessary to check and confirm the positive result and negative result that will help to match with the experiment result.

For positive result adding an indicator to get a definite positive result to mystery food for example gelatin or oil. Similarly for a definite negative result adding it to known food or water.

want or the answer