Final answer:
The metal can touched while a negatively charged balloon is near gets positively charged, and the balloon remains negatively charged. Spheres touching each other distribute charge evenly, and an object that attracts neutral paper and repels a negatively charged balloon is positively charged.
Step-by-step explanation:
When a negatively charged balloon is brought near a neutral metal can mounted on a foam stand, and the can is touched on the opposite side, electrons will flow from the can to the ground because the negative balloon repels the free electrons in the metal. This will leave the can with a positive charge since it loses some of its free electrons. The charge on the balloon remains negative, as the balloon does not lose its excess electrons during this process.
The same principles apply when differentially charged spheres are brought in contact with each other. Charges equalize upon touching. For example, if a sphere A with a charge of –5 nC (nanoCoulombs) and a sphere B with a charge of –3 nC are brought together, charges are shared and each sphere ends up with –4 nC. This process is called charge redistribution or electrostatic induction.
If an uncharged metal sphere is brought near but not in contact with a charged object, no net charge is transferred. However, if it were touched with a positively charged object, it would gain positive charge and remain positively charged after the object is removed.
In the scenario where two negatively charged balloons repel each other and a neutral object is attracted to one, the neutral object (Z) could be either neutral, having undergone polarization, or positively charged, leading to electrostatic attraction.
Finally, if an object attracts neutral pieces of paper but repels a negatively charged balloon, the net charge on the object is positive. The attraction to the neutral paper is due to induced polarization, and the repulsion of the negatively charged balloon is because like charges repel.