Physical Properties Of NO2 by keypoint It is reddish-brown gas. It is easily liquefied into a yellow liquid. It turns damp blue litmus paper red. It is heavier than air. It is poisonous. It has an irritating smell. Others are Viewing: Chemical Properties Of NO2 Nitrogen (IV) Oxide NO2 Physical Properties of Chloride Physical Properties Of Oxygen Physical Properties Of HNO3 Physical Properties of Ammonia Physical Properties of Sulphur