Why solid, liquid and gas have different properties?
It has to do with how the molecules and particles of matter interact in a particular phase.
In solids, the atoms and molecules that make up the object/matter have low energy levels, and are generally locked rigidly into place with each other.
In liquids, the molecules start to have higher energy levels, and this allows the particles to break away from each other and start sliding and slipping around, leading to less density and creating a liquid.
In a gas, the particles of matter that make up the molecules now have so much energy that they’re just bouncing and whizzing around in every direction, becoming even less dense than the liquid phase.
That’s really the reason why they all differ physically, because the molecules in one phase have more energy and are moving around more energetically than in a cooler phase.