Ameasure of how much mass there is in a volume of a substance is

Asingle atom of an element has 21 neutrons, 20 electrons, and 20 protons. which element is it? ok o z

•hydration •dissociation •dissolving which one goes to which

The bone of a dinosaur and the imprint of a leaf are examples of which kind of fossils? a) index b) body c) amber d) trace