Answer:
The leaves of an electroscope will return to their original position if the electroscope is not grounded because the final condition of the electroscope is the same as it was originally.
If however if one touches the terminal of an electroscope while the scope is exposed to a source of static electricity, and then the contact with the terminal is removed before the source of static electricity is taken away, then any excess electrons will remain on the electroscope and the leaves will remain diverged.
