Just to check that I've understood the concept of isomerism: 1. The problem statement, all variables and given/known data How many stereoisomers are possible for a) a 2-ketoheptose b) an aldoheptose c) a ketotriose 2. The attempt at a solution a) First: does the "2" mean that the carbonyl carbon is the second C-atom? The molecule has 4 asymmetric centers and hence 2^4 = 16 possible stereoisomers. b) 5 asymmetric centers, so 2^5 = 32 possible stereoisomers c) No asymmetric centers, therefore 2^0 = 1 possible stereoisomer Correct?