Final answer:
A neutral electroscope is charged by touching it with a positively charged glass rod, resulting in the transfer of electrons and leaving the electroscope with a net positive charge.
Step-by-step explanation:
A neutral electroscope can be charged by touching it with a positively charged object or a negatively charged object. In the scenario provided, the electroscope is charged by touching it with a positively charged glass rod. The glass rod has been charged positively due to the transfer of electrons away from the rod when it is rubbed with silk, leaving an excess of positive charges on its surface. When the positively charged glass rod touches the electroscope, electrons are attracted to the top of the electroscope and transferred to the rod, leaving the electroscope with a net positive charge. This is characterized as charging by contact, where the actual physical contact is necessary for the transfer of electric charge because glass is an insulator and charges do not move easily through it.