Static Electricity - Mission SE3 Detailed Help

Material X has a greater electron affinity than material Y. When two neutral samples of these materials are rubbed together, _______.

Triboelectric Charging
Triboelectric charging (a.k.a., charging by friction) is the charging process that usually involves the rubbing together of two objects of dissimilar materials in order to transfer electrons from one object to the other. The object made of the material with the greatest affinity for electrons is the object that receives the electrons; the object with the lesser affinity for electrons provides the electrons. The process usually involves the rubbing of the two materials because it increases the amount of close intimate contact between the different atoms and allows for more electrons to be transferred.