Question

How many stereoisomers are possible for (a) a ketopentose, (b) a ketohexose, and (c) a ketoheptose?

Short answer

(a) Ketopentose has four possible stereoisomers.

(b) Ketohexose has eight possible stereoisomers.

(c) Ketoheptose has sixteen possible stereoisomers

Step-by-step solution

Concept of stereoisomers

Stereoisomers are generally isomers having the similar composition but having different orientation of their parts.

Number of stereoisomers possible for (a) ketopentose

Ketopentose has five carbon atoms. Thus, there are four stereoisomers possible for a ketopentose.

Number of stereoisomers possible for (b) ketohexose

Ketohexose has six carbon atoms. Thus, there are eight stereoisomers possible for a ketohexose.

Number of stereoisomers possible for (c) ketoheptose

Ketoheptose has seven carbon atoms. Thus, there are sixteen stereoisomers possible for a ketoheptose.