Sound moves through a (blank) or (blank) material when the atoms within the material push against each other , transferring the energy from one particle to the next

With i really need the correct answer!

What happens when chlorine reacts with bromine? a. electrons move from the chlorine atoms to the bromine atoms. b. electrons move from the bromine atoms to the chlorine atoms. c. electrons are shared between the chlorine atoms and the bromine atoms. d. electrons become delocalized among the atoms.

If you put a helium-filled balloon in the refrigerator, what will happen?