Answer: for an object or gas or liquid to float in another there must be a difference in density
Explanation:
Helium has a density of 0.18 kg/m³ and air has a density of 1.29 kg/m^³. If a balloon is filled with helium it will float in air due to density differences
Archimedes' principle states that the upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially submerged, is equal to the weight of the fluid that the body displaces
