Hello. Most thermometers would use mercury, but some use alcohol thanks to its freezing points. Alcohol freezes at -114 Celsius, while water freezes at 0 Celsius. If it was freezing outside, the water would freeze too, making the thermometer useless.
Chemical energy is converted to thermal energy.
Gases= no define volume, no shape and fast particle movement.
Liquid=no define shape,define volume and some particle movement.
Solid= define shape, define volume and no movement
Hope that this helps, lmk if you need clarification