Final answer:
The word 'agitation' refers to a state of shaking or disturbance, and can apply to both physical and emotional contexts. In a physical context, thermal agitation involves the movement of particles due to heat.
Step-by-step explanation:
The meaning of the word agitation most closely aligns with the first option: A shaking or disturbance. This term can refer to a physical state of being agitated, such as when something is stirred or moved around vigorously. It can also describe a psychological or emotional state of feeling disturbed or excited. An example of agitation in a physical context could be the rapid shaking of a bottle of juice before opening. In a chemical context, thermal agitation refers to the movement of atoms and molecules in a substance due to heat, which can cause these particles to emit and absorb radiation. This is distinct from a standing wave, which is a wave that oscillates in place with nodes where no motion happens. Meanwhile, a change that can be seen or felt where the particles are not broken up is a physical change, while the formation of new substances in a chemical reaction relates to a chemical change.