Aheavy planet and a light planet are found to have the same momentum.

what do we know about their speed?

•the heavy planet is faster,

•the light planet is faster,

•they have the same speed.

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.