A plastic rod that has been charged to − 16 nC touches a metal sphere. Afterward, the rod's charge is − 10 nC . What kind of charged particle was transferred between the rod and the sphere, and in which direction? That is, did it move from the rod to the sphere or from the sphere to the rod?

Electron.

From plastic rod to metal sphere.

Explanation:

The charged plastic rod is negatively charged, which means it contains excess electrons.

After they touch each other, the plastic rod now has a more positive value.

Since the sphere is a metal sphere, it is able to conduct the flow of electrons.

Hence, the plastic rod has given off some of its electrons to the metal sphere.