Mary is trying to determine the charge of an object in the lab. she observes that it is repelled by a positively charged rod. what can you say about the charge of the object?

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.