Any method of measuring the age of an object of event in years

Any method of determining whether an event or object is older or younger than other events or objects. The idea that younger rocks lie above older rocks in and undisturbed layer. Any method of measuring the age of an event or object in years. Naturally preserved evidence of animal activity.

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.