What is a black whole why does it exist

If u mean black hole*
It’s a space where gravity pulls so much that even light can not get out. The gravity is so strong because matter has been squeezed into a tiny space. This can happen when a star is dying because no light can get out, people can’t see black holes. They are invisible.

Black holes of stellar mass form when very massive starts collapse at the end of their life cycle.

- info from NASA

The charge of an ion with 55 protons and 52 electrons is +3. the reason is because protons are positive, and there are three more than the amount of negative electrons.