Combine the number of its Protons and Neutrons and you will have its atomic mass.
It will only be valuable if proved correct so it's D
As the atomic radius decreases, it becomes harder to remove an electron that is closer to a more positively charged nucleus. ... They experience a weaker attraction to the positive charge of the nucleus. Ionization energy increases from left to right in a period and decreases from top to bottom in a group.
Answer:
After Eris was discovered, they had to decide whether Eris was a planet or not. If they decided it wasn't a planet, they had to also decide whether Pluto should be counted as a planet since Eris and Pluto were quite similar. They were the same size, and they were both part of the Kuiper Belt.
Explanation: