Draw the structures of two stereoisomeric alkenes that would give 3-hexanol as the only major product of hydroboration

Cis- and trans-3-hexene are symmetric hydrocarons that give only one major product i.e 3-hexanol upon hydroboration.

Explanation:

During hydroboration of 3-hexene, borane (BH3) is added to the double bond of hexene,  that transfers the hydrogen atoms to that carbon which becomes is bonded to the boron. The process of hydroboration is created in two steps that leads to the formation of 3-hexanol and boric acid. (please see figure)

Now, the two stereoisomers, Cis- and trans-3-hexene both will give off the 3-hexanol upon hydroboration and the structure of these are illustrated in the figure.

fe 55.85 g/mol and h2o 18.02 g/mol.