Final answer:
A positive result for the presence of reducing sugars using Tollen's reagent is the appearance of a silver mirror, and using Benedict's reagent is the formation of a red color precipitate.
Step-by-step explanation:
If a reducing sugar is present, the positive results you would observe in the tests include:
- The formation of a silver mirror on the glass when using Tollen's reagent as Ag+ is reduced to Ag.
- The appearance of a red color precipitate in Benedict's test as Cu2+ in the reagent is reduced to Cu2O.
Reducing sugars, such as glucose and fructose, have an aldehydic or ketonic group capable of reducing certain metals when in an alkaline medium. Therefore, upon successful reduction of the metal ions in the reagents, a visual change is observed, confirming the presence of reducing sugars.