Answer:
Test tube 1 would serve as a negative control for the experiment.
Explanation:
Heating of Benedict’s solution in the presence of monosaccharides would change the color. However, when it has no monosaccharides present, the color will stay the same. So, in any experiment where you want to test the presence of monosaccharides (reducing sugars), you are supposed to heat the Benedict’s solution alone too so that you know that there was no contamination in the solution itself and then you can compare the results of test samples.
