Answer:
4 is answer. Explain how you know it is emit or absorb.
Step-by-step explanation:
U-238 is a radioactive isotope of uranium, meaning it undergoes radioactive decay. Specifically, U-238 undergoes alpha decay, which involves the emission of an alpha particle. An alpha particle is composed of two protons and two neutrons, which is equivalent to a helium-4 nucleus.
The fact that U-238 is unstable and undergoes alpha decay can be determined based on its nuclear properties. U-238 has an atomic number of 92, indicating it has 92 protons in its nucleus. However, its atomic mass is 238, suggesting it has more than 92 nucleons (protons and neutrons) in its nucleus. This indicates the presence of additional neutrons in the U-238 nucleus.
The extra neutrons in the U-238 nucleus make it unstable and prone to decay. To achieve a more stable configuration, U-238 spontaneously emits an alpha particle from its nucleus. This emission reduces the number of protons and neutrons in the nucleus, resulting in the formation of a different nucleus.
Therefore, based on the radioactive properties of U-238, it is known to be unstable and spontaneously emit alpha particles during the process of radioactive decay.