What is the scientific name of particles which make up matter?

When an incense stick(agarbatti) is lighted in one corner of a room, its fragrance spreads in the whole room quickly. Which characteristic of the particles of matter is illustrated by this observation?

A piece of chalk can be broken into small particles by hammering but a piece of iron cannot be broken into small particles by hammering. Which characteristic of the particles of matter is illustrated by these observations?

Name the process by which a drop of ink spreads in a beaker of water.

What is the general name of:

(a) rigid form of matter?

(b) fluid forms of matter?