What is the definition of oxygen

Which property of fossils allow scientists to determine the relative rock ages..

Edward tolman explained the results of his study by theorizing that the rats were learning about the maze during every trial but they a. were agitated because other groups were getting reinforcement b. could not remember how to demonstrate it without reinforcement c. were not motivated to demonstrate it without reinforcement d. seemed to be too lazy to actually work without reinforcement

What are chlorofluorocarbons and what impact do they have on the atmosphere?