Extinction occurs when a is no longer paired with a

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?

Which of the following is not a potential result of deforestation?

The changes that the students observed, rapid breathing and sweating, would be classified as a to a change in a system.