Q: Radioactive isotopes are characterized by an unstable what? Choices: - shell - proton - electrons - nuclei A:
nuclei

Q: What changes from heat or pressure during metamorphism? Choices: - carbohydrates - grains - fossils - minerals A:
minerals

Q: Each silicon atom shares how many valence electrons with other silicon atoms in a crystal? Choices: - five - ten - three - four A:
four