To determine which among the options is a reducing sugar, we first need to understand what a reducing sugar is. Reducing sugars are carbohydrates that possess a free aldehyde group or a free ketone group and have the capability to reduce certain chemicals, such as Benedict's solution or Fehling's solution, from which we can infer their chemical identity.
Many common monosaccharides (like glucose and fructose) are reducing sugars. Among disaccharides, sucrose is known as a non-reducing sugar because the glycosidic bond in sucrose does not allow either of the ring forms to open up and provide a free aldehyde or ketone group.
Below, let's examine the possible options using the given images to identify the reducing sugar:
After reviewing the images of the chemical structures:
- This depicts glucose, a common reducing sugar due to its free aldehyde group when in open-chain form.
, , - These are structural representations of non-reducing sugars or sugars without a free aldehyde or ketone group.
Thus, the correct answer is the image representing glucose, which is a reducing sugar. This is the first option and is confirmed with the given correct answer information.
In conclusion, when identifying reducing sugars, always look for the presence of a free carbonyl group (either an aldehyde or a ketone in its open-chain form). Glucose, represented by the first image, is a classical example of a reducing sugar.
