Cycloheptyne looks kind of like an envelope: 6 C-atoms are more or less in a plane and one methylene group is out of that plane. The molecule visibly suffers from ring strain! While the C-atoms in triple bonds formally are sp-hybridized and linear, it is clear that the size of the ring does not allow for such linearity. Take a good look at this molecule and decide whether it is chiral. If it is chiral, then you need to decide whether the molecule can be easily converted into its enantiomer. If the latter is true, then there won't be any optical activity.