The carbohydrates in which the following properties are found are called reducing sugars. The reduction of Tollen’s reagent, Fehling’s solution, Benedict’s solution. All monosaccharides are reducing sugars. Contrary to this the carbohydrates in which the above properties are not found are called non-reducing sugars. For example, sucrose, starch, cellulose, etc. The disaccharides, in which carbonyl group of any one monosaccharide from both the monosaccharides, is present as hemiacetal or ketal and does not involve in glycosidic linkage formation, are reducing. For example, maltose and lactose. Two diastereomeric monosaccharides are called epimers when their configuration differs only at stereogenic centre. Monosaccharides form glycoside with alcohol in the presence of an acid. All monosaccharides show mutarotation.

Which of the following reagents may be used to identify glucose?

Ammoniacal \(AgNO_3\) solution

The correct answer is option 2. Ammoniacal \(AgNO_3\) solution.

The identification of glucose involves detecting its characteristic properties, particularly its reducing nature. Glucose, like many other reducing sugars, has the ability to donate electrons to other substances, thereby reducing them. One common method to identify glucose is through a chemical reaction called the Tollens' test, which uses ammoniacal silver nitrate \((AgNO_3)\) solution.

Here is how the Tollens' test works:

Preparation of Tollens' Reagent: Tollens' reagent is prepared by adding aqueous ammonia \((NH_3)\) to silver nitrate \((AgNO_3)\) solution. This forms a complex known as ammoniacal silver nitrate.

Reaction with Glucose: When a solution containing glucose is mixed with Tollens' reagent, the aldehyde group of glucose undergoes oxidation. This oxidation reaction reduces the silver ions \((Ag^+)\) in the Tollens' reagent to metallic silver \((Ag^0)\).

Formation of Silver Mirror: As metallic silver is formed, it precipitates out of solution and coats the inner surface of the reaction vessel. This results in the formation of a silver mirror on the inner walls of the test tube or container.

Observation: The presence of a silver mirror is a positive indication of the presence of glucose in the solution. The intensity of the silver mirror may vary depending on the concentration of glucose in the solution.

Overall, the Tollens' test provides a qualitative method for identifying the presence of reducing sugars like glucose in a given solution. It's a reliable and widely used test in biochemical and analytical chemistry laboratories for carbohydrate analysis.