Re: What state of matter is smoke?

Smoke consists of tiny (microscopic or even smaller) particles of solid 
suspended in the air. So it is really a two phase system -- solid and gas.
It is properly called a solid aerosol.

Systems with one phase very finely divided in another like this are called 
coloidal systems. There are many different sorts. Muddy water sometimes 
contains fine clay particles that cannot be filtered off. A solid in liquid 
system like that is called a sol. Milk is actually a liquid in liquid 
dispersion, called an emulsion. It contains tiny droplets of oil dispersed 
in water. Solid or liquid in gas dispersions are known as solid or liquid 
aerosols. They include fumes, smokes, haze, fog. One interesting type of 
colloidal system is opal, where the lights are caused by sub-microscopic 
droplets of water included in the solid mineral.