Question

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. to practice measuring volume using the graduated pipette correctly to match the mystery food sample to a definite positive result (gelatin, oil, etc.) to match the mystery food sample to a definite negative result (water) to increase the amount of data.

Explanation:

Adding indicator to known substances (positive and negative controls) helps in accurately interpreting results of the mystery food sample. Matching to positive and negative results provides a reference for identification. Increasing data amount improves reliability. Measuring volume is not the main reason here.

Answer:

• to match the mystery food sample to a definite positive result (gelatin, oil, etc.)
• to match the mystery food sample to a definite negative result (water)
• to increase the amount of data