Question

Which expands most for increases in temperature: solids, liquids, or gases?

Answer 1

Can you fill a hot air balloon with water?

Explanation:

Will it float? Well, it won't float in air. Given a gas, MOST of the volume it occupies is EMPTY. If we heat the gas, molecular motion increases to such an extent that the gaseous particles will occupy MORE VOLUME, and the container (whatever it is) will expand in volume, displacing the ambient air. (Of course this underlies hot-air ballooning: heat the gas up enuff, and the balloon will displace a volume of air whose mass is greater than the balloon, and the gondola, and the balloon will float in air.)

On the other hand, for condensed phases, solids and liquids, temperature changes only MARGINALLY affect volume, and thus the density is more or less constant.