Explain, using the particle theory, why
(i) the solid, sodium chloride, has a fixed shape,

because the particles in a solid are more closer to each other than the liquid and gas particles. So the closeness if the particles give a particular shape for the substance.

Please add me to the brainleist please

the molecules move in straight line until they collide with each other or with the walls of the container. collisions are perfectly elastic; when two molecules collide, they change their directions and kinetic energies, but the total kinetic energy is conserved.

explanation:

nanotechnology is a powerful tool in biomaterials research as it creates numerous possibilities for the engineering of functional molecules. nano-bio refers to projected ability to incorporate biomimicry into various materials at nanoscale.