two students stand at rest, facing each other on frictionless skates. they then start tossing a heavy ball back and forth between them.

What happens to an isotope during radioactive decay?

What equation is used to calculate the weight of an object on a plant ?

What do the atoms of elements in the same group have in common? a. they have the same atomic numbers. b. they have the same average atomic masses. c. they have the same number of electron shells. d. they have the same number of electrons in their outermost shells.