What is the maximum number of electrons an f-orbital will hold?

Which of these conditions most likely produces an unstable isotope?

Mary is conducting an experiment on how pollution affects plant growth. how can she ensure that her data are reliable?

Harry lives in a city, and he has a lung condition known as asthma. on certain days, harry has to stay inside because pollutants in the air make it difficult for him to breathe. which of these pollution sources are nonpoint sources that might bother harry if he goes outside? choose the two that apply.