A black hole can't really form inside of another black hole. If you think of a black hole forming after a star goes supernova, then there isn't really a star to go supernove inside of the already created black hole. In fact, there isn't even any space inside of the blak hole for anything to happen. Two black holes can join together, but they wil eventually go to one.
It starts taking in matter.
In a black hole, gravity is so strong that nothing, not even light, can escape. This means that whatever goes into a black hole is trapped inside forever, making the saying "what happens in a black hole stays in a black hole" true.
That's not exactly what happens. What really happens is that they just absorb each other and become a bigger black hole.
The object swallowed by the black hole is destroyed; its mass is added to the mass of the black hole.
Any matter that enters the black hole will be destroyed. Also, it will increase the black hole's size.
It evaporates.
evaporation
Its called a Super Black-hole and scientists believe it is what holds all galaxies together.
They will merge to form a single black hole with the combined mass of the town that merged.
Objects which approach a black hole will get sucked into it.
It gets bent toward the black hole's singularity.
The force of the impact will still be absorbed by the black hole. By definition, a black hole is a very dense mass where no form of radiation can escape - not even light. Since no explosion is faster than light, a black hole would absorb the blast, the impact, and all forms of light and radiation that would be emitted from the bomb. If you were to watch a black hole, you would see no changes from it.