Which state of matter has the slowest moving particles?
Solid has most closely packed particles. They are hard to compress. The particles in solid are generally linked to each other through electrostatic forces. They barely move when force is applied (unless it's brittle). They don't get enough space to move around as a result their speed decreases , they can't keep their usual speed like in gaseous or liquid state. When they try to move, they get attracted towards the particles around them. It becomes extremely difficult for them to keep that maximum speed.