Final answer:
The charge on an acrylic rod after being rubbed with silk and attracting polystyrene foam is most reasonably estimated at 1x10⁻⁸ C; this small charge is consistent with common static electricity magnitudes generated by friction.
Step-by-step explanation:
The phenomenon described in the question involves friction and static electricity. When an acrylic rod is rubbed against a silk cloth, electrons are transferred from one material to the other due to friction. This transfer causes the acrylic rod to become charged, and a similar process occurs with the glass rod and silk cloth. Since like charges repel and opposite charges attract, the charged acrylic rod attracts the polystyrene foam due to electrostatic forces.
Regarding the estimated amount of charge on the rod after being charged by friction, typical electrostatic experiments of this nature result in very small charges. These charges are commonly measured in microcoulombs (μC) or even smaller units. Therefore, the most reasonable estimate of the charge on the rod would be option A, 1x10-8 C. Options B, C, and D suggest much larger amounts of charge, which are unrealistic for static electricity generated by the friction of rubbing small everyday objects.