I can answer one of those...
In solids, the particles are just barely vibrating, and have their own shape. In liquids, the particles are moving more, and they are sliding around and moving places. Their shape can change based on the container they’re in, but the volume stays the same. The particles in a gas are moving very fast, and are far away from each other. A gas can change its volume and shape. If you want to do plasma, that’s when the particles are moving so fast that they can create light. I was going to do the variable thing but it would sound weird and very wordy if I tried to explain it.
Written by a 6th grader who is currently learning about states of matter :P