A five-carbon aldose has three chiral centers and can have up to eight stereoisomers.

### Why this is right In an open-chain five-carbon aldose, the aldehyde carbon and terminal carbon are not chiral, leaving three chiral centers. The maximum number of stereoisomers is $2^n$, where $n$ is the number of independent chiral centers, so $2^3 = 8$. ### The concept This count assumes no internal symmetry reduces the number of distinct forms. The same rule helps estimate stereoisomer counts for other molecules with multiple chiral centers. ### Terms - **Stereoisomer**: a molecule with the same atom connectivity but a different three-dimensional arrangement. ### Remember For $n$ independent chiral centers, the maximum is $2^n$ stereoisomers.