係唔係所有物質都可以change state？

Yes

At room temperature, air is a gas, since it's boiling point is lower than the room temperature;
water is a liquid since it's freezing point is below room temperature;
iron is a solid since it's melting point is higher than room temperature.

E=ml (energy = mass * latent heat of fusion or vaporization)
This is the equation used to calculate the amount of energy needed to change states of matter.
When ice is heated, it gains energy. It will stay at 0 degree celsius until a certain amount of energy (E=ml) is gained.

視乎 溫度 壓力
理論上有一定的能力就得

理論上是對的.

理論上係，只要你有一定能量就得。