Nitrogen Dioxide (NO2): A reddish-brown toxic gas with a characteristic sharp, biting odor. It's one of several nitrogen oxides and plays significant roles in atmospheric chemistry and air pollution.
Oxidation Reaction: A chemical reaction where a substance loses electrons or increases its oxidation state. Like when iron reacts with oxygen to form rust (iron oxide).
Rocket Propellant: The reaction mass that is expelled from a rocket engine in the form of a fluid jet to produce thrust. It consists of fuel and an oxidizer.