In a conventional optical microscope, objects less than about 200 nanometers apart cannot be distinguished from one another. ... Although electron microscopes produce a detailed image of very small structures, they cannot provide an image of the proteins that make up those structures.
As solid is a hard surface and it can be changed to any shape although it is placed to any container whereas liquid can be poured from one container to another and gases have less bulk so they are not exaggerated by gravity
