nitrogen dioxide

colour: brown gas

odour: choking
NO2 is an acidic gas and is toxic and irritating to respiratory system

boiling point: 21.1deg Celsius
NO2 looks a very dense gas and can be liquefied by pressure little higher than the room one

solubility: very soluble
due to its V-shape molecules, considerably strong attraction between water and NO2 molecules is formed so that reaction occurs.
2NO2(aq) + H2O(l) --> HNO2(aq) + HNO3(aq)

nitrogen dioxide is used to converted to nitric acid to produce fertilizers and explosives by industrial process.

The term nitrogen oxide is a general term and can be used to refer to any of these oxides (oxygen compounds) of nitrogen, or to a mixture of them:

Nitric oxide (NO), nitrogen(II) oxide
Nitrogen dioxide (NO2)
Dinitrogen monoxide (N2O), nitrous oxide
Dinitrogen trioxide (N2O3), nitrogen (III) oxide
Dinitrogen tetroxide (N2O4)
Dinitrogen pentoxide (N2O5)
A mixture is often formed in chemical reactions that produce nitrogen oxides, with the proportions depending on the specific reaction and the conditions it is performed in. This is one reason why home production of N2O is undesirable; the other two stable oxides — which are extremely toxic — are liable to be produced.
MORE DETAIL:http://en.wikipedia.org/wiki/Nitrogen_oxide