When gases are compressed, the particles are forced closer together.

Gases can be compressed easily because there is a large amount of space between the individual molecules, which are very active and move around at high speed. When gases are compressed, the particles are forced much closer together, allowing a huge amount of particles to fit a small space.

Well to my expert knowledge and my exquisite calculations i think the the negative ion # 412 is the key to sucess

Aphysical change is one that you can put in and remove like a ham sandwich. the stuff you put in there can be changem its not permanet. a chemical change is on that can't be change thats permanet. like when you make a cake and bake it. you can't get those ingredients back.