Which of the following is a true statement about atomic nuclei? (A) They are made up of protons, neutrons, and electrons (C) Every atomic nucleus has the same number of particles (D) The atomic nucleus has no relation to an atom's mass

Atomic nuclei are primarily composed of protons and neutrons, which are collectively known as nucleons. Electrons, however, exist outside the nucleus and are not part of it. This means that option (A) is incorrect! Nuclei vary in particle numbers, so the number of nucleons changes with different elements, making (C) false. Additionally, the atomic mass is predominantly derived from the mass of the nucleons within the nucleus, which means (D) is also incorrect. The only true statement is that all nuclei consist of protons and neutrons! If you dive into the world of atomic structure, you'll discover a fascinating history! For instance, the description of the atomic nucleus was revolutionized by Ernest Rutherford in 1911, who proposed that atoms consist of a small, dense nucleus surrounded by orbiting electrons, following his famous gold foil experiment. This laid the groundwork for modern atomic theory! In the real world, atomic nuclei play a crucial role in various applications, including nuclear energy production and medical imaging. For instance, the principles of nuclear fission are harnessed in power plants to generate electricity, while radioactive isotopes are used in PET scans to visualize metabolic processes in the body. Understanding atomic nuclei is a key foundation for many advanced technologies today!