Which of the following organic reactions results in a product mixture that is optically active?
(Assume any single enantiomer reactant used is 100% optically pure.)
The nucleophilic addition of HCN\text{HCN}HCN to pentan-3-one
The acid-catalysed dehydration of a single enantiomer of butan-2-ol
The SN1\text{S}_\text{N}1SN1 hydrolysis of a single enantiomer of 3-bromo-3-methylhexane
The SN2\text{S}_\text{N}2SN2 hydrolysis of a single enantiomer of 2-bromobutane