The disintegration of radioactive substances occurs at a predictable rate.
If a uranium atom absorbs a neutron it will be unstable, and will generally split into two fragments. This process, the splitting of a large nucleus into two smaller ones, is known as NUCLEAR FISSION.
Hope this helps
I'm not sure about part 1, you may need to google it, but part two is 11 protons, 11 electrons and 12 neutrons. You can find protons and electrons by just looking at the atomic number, and you can find neutrons by subtracting the atomic number from the atomic mass.