Question

If a balloon is rubbed on a jumper the balloon will charge up with a negative charge.
Explain how the balloon becomes charged.

Answer 1

Static electricity arises when the free electrons on the surface of a donor object (e.g., a balloon) are transferred through contact to a receiver body (e.g., a jumper). That leaves the donor body with a dearth of free electrons on its surface. And that lack of electrons is what we call positive charge. It really isn't; it's just less negative than the recipient body.

So if your balloon transfers electrons to the jumper, then the jumper will have more than its fair share of free electrons on the surface and be negatively charged... at least temporarily. As I've no clue what your jumper consists of I can't really say what happens to those excess electrons from the balloon. They may stay on the surface or they may immediately drift inward and distribute throughout the material of the jumper.

More than likely the electrons will disperse throughout the jumper. In which case the jumper will not be negatively charged to the extent that it could in turn pass its excess electrons on to another recipient body. In this case, the jumper acts as a ground, which is why the electrons would jump from the balloon in the first place. Electrons always seek ground level.