An empty party balloon will float to the ceiling of a room once it is filled with helium.
AWhat does this tell you about the density of air in the room compared to the density of helium?
BFor the balloon to float in air, what two factors might have changed about the balloon?
Answer those two questions of you know the answer.
AWhat does this tell you about the density of air in the room compared to the density of helium?
BFor the balloon to float in air, what two factors might have changed about the balloon?