How many chiral carbons are present in the open-chain form of a ketopentose?

Question

Quizplus · Accepted Answer

A ketopentose is a five-carbon sugar with a ketone functional group. The open-chain form of a ketopentose has five carbon atoms, all of which are chiral. However, the ketone group breaks the symmetry of the molecule, and one carbon adjacent to the ketone will have only three different groups attached to it, making it achiral. The other four carbons will have four different groups attached to them, making them chiral. Therefore, there are two chiral carbons in the open-chain form of a ketopentose.

How Many Chiral Carbons Are Present in the Open-Chain Form