Is nitrogen dioxide a greenhouse gas?
Nitrogen Dioxide is a greenhouse gas
In short no. It is however one of the main contributors to acid rain and sulphur dioxide dissolves in rain water to form sulphurous acid. The main greenhouse gases are carbon dioxide, methane and nitrogen oxides (which also causes acid rain). Nitrogen oxide is a small percentage greenhouse gas (approx 6-7%) but is still significant because it is about 300 times more potent that carbon dioxide at 'trapping' solar radiation.
Depends on your understanding of the term "biggest": The largest volume of naturally occurring greenhouse gas is water vapour. The largest volume or tonnage of manmade greenhouse gases is carbon dioxide. The most potent is Sulfur Hexafluoride (SF6) which has a greenhouse gas impact 23,900 times that of carbon dioxide.