Female killer whales stop reproducing in their . 50s-60s, 60s-70s, 40s-50s, 30s-40s

The circles, or orbits, for electrons are called energy levels. each level can hold only a certain number of electrons. add electrons to each level until you can't add any more. how many electrons can each level hold?

Radiometric dating is used to tell the absolute age of materials by studying the decay rate of radioactive isotopes. the decay rates of isotopes are constant and are expressed as .

Name the tissue types that form the wall of each organ in questions 7-10