Which describes the substances that form covalent bonds

Compare and contrast physical changes with chemical changes.

Acontrol during an experiment. might change remains constant does not exist does change

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.