Question

Which of the following is used for deduction of glucose?

• A. Fehling solution A&B
• B. Benedict's solution
• C. Both a&b
• D. Milon's reagent

Answer 1

The correct option is C

Both a&b

Explanation for the correct option:

(C) Both a&b

Fehling solutions A & B:

• Fehling's A is a deep blue aqueous solution of Copper(II) sulphate$\left({\mathrm{CuSO}}_4\right)$.
• Fehling's B, which is a colorless solution of aqueous Potassium Sodium tartrate (also known as Rochelle salt) made strongly alkali with sodium hydroxide$\left(\mathrm{NaOH}\right)$.
• Fehling's solution is used to test for monosaccharides. The most important application is to detect reducing sugar like glucose.
• Excess glucose in blood and urine can lead to diabetes.

Benedict's reagent

• Benedict's solution is used to test for simple sugars, such as glucose.
• It is a clear blue solution of sodium and copper salts. In the presence of simple sugars, the blue solution changes color to green, yellow, and brick-red, depending on the amount of sugar.
• Benedict's solution is a chemical reagent and complex mixture of Sodium carbonate(${\mathrm{Na}}_2{\mathrm{CO}}_3$), Sodium citrate, and Copper(II) sulfate pentahydrate(${\mathrm{CuSO}}_4.5{\mathrm{H}}_2\mathrm{O}$).

Explanation for incorrect options:

(D) Milon's reagent

• Millon's reagent is used to detect the presence of soluble proteins.
• A few drops of the reagent are added to the test solution, which is then heated gently. A reddish-brown coloration or precipitate indicates the presence of tyrosine residue which occurs in nearly all proteins.
• Millon's reagent is a solution of Mercurous nitrate and Mercuric nitrate in Nitric acid$\left({\mathrm{HNO}}_3\right)$-containing little Nitrous acid$\left({\mathrm{HNO}}_2\right)$.

Hence, option (C) is correct. Fehling solution A&B, Benedict's solution both are used for deduction of glucose.