Answer:
B) Make sure spheres are not in contact with each other. Rub the glass rod on the silk to charge the rod positively (hence to charge piece of silk negatively). Touch one of the spheres with the glass rod then touch another one with the piece of silk.
Explanation:
In static electricity, frictional rubbing can excite electrons, and make them jump from one material to another. Rubbing the glass rod and the silk together makes electron flow from the glass rod to the silk piece. On separation, the rod and silk will be seen to have equal amount of charge but, the glass rod will be positively charged from losing electron, and the silk piece will be negatively charged from gaining extra electrons. When they are each made to touch the metal spheres that are not in contact, the spheres will acquire equal amount of charges opposite the charge on the material that was used to charge them.
