Why a charged electroscope will discharged when placed near a radioactive material?

1.

Electroscopes can be used to detect electronic charges and when a electroscope is given negative charges they repel each other and spread apart. They will remain apart until their electrons have somewhere to go and it combines with positive charges. When nuclear radiation is moving through the air it can remove electrons from some molecules In the air and cause other molecules in the air to gain electrons. - B0N3S