Q12 / 180 · COMEDK 2026 (9 May Shift 1) · Chemistry
Which among the following is an INCORRECT statement?
- APolysaccharides are known as non-sugars as they are not sweet in taste
- Correct answerBIn monosaccharides, aldoses are reducing sugars while ketoses are non-reducing sugars
- CIn D (+) Glucose, D represents the configuration similar to D-Glyceraldehyde
- DD (-) fructose forms a five membered ring known as furanose which is in analogy with the compound furan
Solution
All monosaccharides, whether aldoses or ketoses, are reducing sugars. Ketoses such as fructose can reduce Tollens' and Fehling's reagents because they undergo isomerization to aldoses in the alkaline medium via an enediol intermediate. Thus, the statement that ketoses are non-reducing sugars is incorrect.
Polysaccharides are indeed called non-sugars because they are not sweet in taste.
The 'D' in D-(+)-Glucose indicates that the configuration at the highest numbered chiral carbon is the same as that of D-Glyceraldehyde.
D-(-)-Fructose exists as a five-membered cyclic structure called furanose, which is named by analogy to the heterocyclic compound furan.
Answer: In monosaccharides, aldoses are reducing sugars while ketoses are non-reducing sugars
Polysaccharides are indeed called non-sugars because they are not sweet in taste.
The 'D' in D-(+)-Glucose indicates that the configuration at the highest numbered chiral carbon is the same as that of D-Glyceraldehyde.
D-(-)-Fructose exists as a five-membered cyclic structure called furanose, which is named by analogy to the heterocyclic compound furan.
Answer: In monosaccharides, aldoses are reducing sugars while ketoses are non-reducing sugars
Hence, the correct answer is option: 'B'.