Structure of D mannose is :

Structure of L mannose will be:

The carbon atom that has four separate atoms or groups of atoms linked to it is the stereogenic centre. The functional groups found in Structures have the same molecular formula. We are aware that L-mannose, D-glucose, and D-galactose are all aldose (containing aldehyde group) sugars, but D-fructose is a ketose sugar (having ketone group). D-fructose can thus be outright ruled out as one of our solutions. In this instance, it is necessary to investigate the L-Mannose structure as well as the other choices that have been mentioned. The L-mannose molecule is composed of: