Identify a D-2-Ketopentose from Among the Following Compounds

Question

Identify a D-2-ketopentose from among the following compounds.
A) D-erythrulose
B) D-psicose
C) D-ribulose
D) D-fructose

Accepted Answer

D-ribulose is a D-2-ketopentose because it is a pentose sugar (5 carbons) with a ketone functional group (C=O) on the second carbon from the top. D-erythrulose is also a pentose sugar but with an aldehyde functional group (CHO) on the second carbon, making it a D-erythro-pentose. D-psicose and D-fructose are both hexose sugars with ketone functional groups on different carbons, making them D-ketohexoses.