Question

Atom makes molecule exist in constant motion give example

Answer 1

All atoms are in constant motion because this universe has energy of some kinds. Temperature is just a concept that human beings use to describe the movement of atomes/molecules. When we "increase temperature", it's nothing other than we increase the movement of the molecules somehow, say put an electric heater under the kettle: the high movement of the atoms in the heater will transfer to the kettle and then the water inside it.

Reference https://www.physicsforums.com/threads/why-are-atoms-in-constant-motion.344070/