Question

How many aldose, ketose, furanose, pyranose and hemiacetal units are present respectively in the following molecule?

• A. $2,0,0,2,1$
• B. $1,1,1,1,2$
• C. $0,2,0,2,1$
• D. $2,0,0,2,2$

Answer 1

The correct option is A $2,0,0,2,1$

In the said molecule, there are two aldehyde groups, one in each unit. So that makes 2 aldoses and zero ketose. Both units are six membered rings called pyranose. There are 2 pyranose and 0 furanose rings. There is one hemiacetal unit while the other is used up in glycosidic linkage.