Answer
The random molecular motion of a substance is greatest when the substance is a gas
Step-by-step explanation
A matter is something that has mass and occupies space.
Matter can be divided into gas, liquid, and solid. Among these forms of matter, changes can occur. For example:
liquid to gas: evaporate
gas to liquid: condenses
solid to liquid: melting
liquid to solid: freeze.
The increasing order of random molecular motion of all these forms of matter is gas > liquid > solid.