Benedict's Test Color Scale for Reducing Sugars

Steps:

• Benedict's solution starts blue and changes color when heated with reducing sugars, indicating concentration.
• Color sequence reflects increasing sugar levels: blue (none) to green (trace), yellow (low), orange (moderate), red (high), brown (very high).
• The question asks for the lowest concentration among colored results, excluding the original blue.
• Green corresponds to the minimal detectable reducing sugar amount.

Why B is correct:

• In Benedict's test, green precipitate forms at the lowest positive concentration of reducing sugars, as defined by the qualitative scale for aldehyde or ketone groups reacting with Cu²⁺ to form Cu₂O.

Why the others are wrong:

• A. Brown indicates the highest concentration, with brick-red to brown precipitates from excess sugar reduction.
• C. Red signifies high concentration, following orange in the progression.
• D. Yellow represents a moderate-low concentration, above green but below orange.

Final answer: B