You enter a room and notice a distinctive new smell. after a bit of time you no longer smell the odor. this illustrates the phenomenon of

This is olfactory fatigue, also known as odor fatigue.

Ifound the exercise on the internet. attached is the list mentioned above.in order for a compound to be considered optically active it can't have any axis or plan of symmetry. the molecule  shouldn't also  be superimposable on its mirror image.with such considerations, the compounds that are optically active are: -third compound on the first image is optically active; -second and third compound from the second image are optically actives.

The correct answer is connotation.