Q: Radioactive isotopes are characterized by an unstable what? Read this paragraph and choose the correct option from the provided answers: You may have seen this sign beforemaybe in a hospital. The sign means there is danger of radiation in the area. Radiation consists of particles and energy that are given off by radioactive isotopes, which have unstable nuclei. But you don't have to go to a hospital to be exposed to radiation. There is radiation in the world all around you. Choices: - shell - proton - electrons - nuclei A:
nuclei

Q: What changes from heat or pressure during metamorphism? Read this paragraph and choose the correct option from the provided answers: Metamorphism does not cause a rock to melt completely. It only causes the minerals to change by heat or pressure. If the rock melts completely, it will cool to become an igneous rock. Choices: - carbohydrates - grains - fossils - minerals A:
minerals

Q: Each silicon atom shares how many valence electrons with other silicon atoms in a crystal? Read this paragraph and choose the correct option from the provided answers: Each silicon atom has four valence electrons it shares with other silicon atoms in a crystal. A semiconductor is formed by replacing a few silicon atoms with other atoms that have more or less valence electrons than silicon. Choices: - five - ten - three - four A:
four