Estimate the amount of reducing sugar in the given solution by Benedict's method. Standard glucose (1 mg/mL) is provided.

1. 1 · Aim. To estimate the reducing sugar in the given solution by Benedict's quantitative method.
2. 2 · Principle. Reducing sugar reduces Cu2+ in boiling alkali; potassium thiocyanate turns Cu+ into white cuprous thiocyanate, so the end point is the disappearance of blue. 25 mL reagent ≡ 50 mg glucose; the exact value is found with standard glucose.
3. 3 · Requirements. Benedict's quantitative reagent, anhydrous sodium carbonate, porcelain bits, standard glucose (1 mg/mL), unknown; burette, pipette with bulb, conical flasks, burner.
4. 4 · Procedure.
   • 10 mL reagent + 1-2 g sodium carbonate + porcelain bits; boil.
   • Titrate with standard glucose, boiling throughout, to the disappearance of blue; get concordant titres.
   • Repeat with the unknown (made up to 100 mL).
5. 5 · Observation. [Table: burette readings for standard and unknown, rough and concordant titres]
6. 6 · Calculation. 10 mL reagent ≡ 19.6 × 1 = 19.6 mg glucose. Sugar in 100 mL = 19.6 × 100 ÷ 12.4 = 158.1 mg.
7. 7 · Result. The given solution contains ____ mg reducing sugar (as glucose) per 100 mL.
8. 8 · Precautions. Keep boiling; add dropwise near the end; concordant titres; goggles and gloves; never pipette by mouth.

Scoring tip: Show the formula with units before putting in numbers, and give the result per 100 mL. Most lost marks are from a missing standard titre.