When someone who has put on perfume enters a room, the fragrance is soon smelled in other parts of the room. Explain in terms of the movement...

The short answer is
diffusion.

According to kinetic molecular theory, all
particles of all substances are in constant motion as long as the temperature is above
absolute zero.

In solids, the motion is mainly the internal
vibration of atoms of the substance, but in liquids and gases the individual particles
can move about.

You can see this in a liquid if you place a
tea bag on top of a container of water. Over time the tea diffuses into the water and
the entire container becomes tea. The rate at which this takes place depends on the
temperature with diffusion occurring faster as the temperature
increases.

In the case of the perfume, perfume is very
volatile. This means it easily changes from a liquid to a gas at room temperature. When
you spray the perfume, tiny droplets of the liquid are atomized into the air where they
quickly evaporate. The gas particles move randomly about, diffusing into surrounding air
in the room, becoming more dilute as they spread out. Soon the entire room contains some
of the perfume molecules.

Of course this is also true for
the odor of a skunk, rotten eggs, and leaking natural gas.