Answer:
Atoms consist of three basic particles: protons, electrons, and neutrons. The nucleus (center) of the atom contains the protons (positively charged) and the neutrons (no charge). The outermost regions of the atom are called electron shells and contain the electrons (negatively charged).
Answer:
The height of A is 900
Explanation: Beside A, there is a number which explains what the height is so the answer is A.
It addressed the problem concerning why electrons didn't fall into the positive nucleus. HOPE THIS HELPS BRAINLIEST PLEASE